ARM: OMAP2+: use IS_ERR_OR_NULL() helper

Simplify error handling in OMAP powerdomain, voltage, and VP code by
replacing open-coded '!ptr || IS_ERR(ptr)' checks with the combined
IS_ERR_OR_NULL() helper.

This improves readability and consistency across
omap_set_pwrdm_state(), voltdm_get_voltage(), voltdm_scale(),
voltdm_reset(), and related functions.

No functional change intended.

Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
Reviewed-by: Andreas Kemnade <andreas@kemnade.info>
Link: https://lore.kernel.org/r/20250817083449.2249268-1-yangxiuwei2025@163.com
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

Author: Yang Xiuwei

arch/arm/mach-omap2/powerdomain.c

@@ -1111,7 +1111,7 @@ int omap_set_pwrdm_state(struct powerdomain *pwrdm, u8 pwrst)
 	int curr_pwrst;
 	int ret = 0;
 
-	if (!pwrdm || IS_ERR(pwrdm))
+	if (IS_ERR_OR_NULL(pwrdm))
 		return -EINVAL;
 
 	while (!(pwrdm->pwrsts & (1 << pwrst))) {

arch/arm/mach-omap2/voltage.c

@@ -51,7 +51,7 @@ static LIST_HEAD(voltdm_list);
  */
 unsigned long voltdm_get_voltage(struct voltagedomain *voltdm)
 {
-	if (!voltdm || IS_ERR(voltdm)) {
+	if (IS_ERR_OR_NULL(voltdm)) {
 		pr_warn("%s: VDD specified does not exist!\n", __func__);
 		return 0;
 	}
@@ -73,7 +73,7 @@ static int voltdm_scale(struct voltagedomain *voltdm,
 	int ret, i;
 	unsigned long volt = 0;
 
-	if (!voltdm || IS_ERR(voltdm)) {
+	if (IS_ERR_OR_NULL(voltdm)) {
 		pr_warn("%s: VDD specified does not exist!\n", __func__);
 		return -EINVAL;
 	}
@@ -124,7 +124,7 @@ void voltdm_reset(struct voltagedomain *voltdm)
 {
 	unsigned long target_volt;
 
-	if (!voltdm || IS_ERR(voltdm)) {
+	if (IS_ERR_OR_NULL(voltdm)) {
 		pr_warn("%s: VDD specified does not exist!\n", __func__);
 		return;
 	}
@@ -154,7 +154,7 @@ void voltdm_reset(struct voltagedomain *voltdm)
 void omap_voltage_get_volttable(struct voltagedomain *voltdm,
 				struct omap_volt_data **volt_data)
 {
-	if (!voltdm || IS_ERR(voltdm)) {
+	if (IS_ERR_OR_NULL(voltdm)) {
 		pr_warn("%s: VDD specified does not exist!\n", __func__);
 		return;
 	}
@@ -182,7 +182,7 @@ struct omap_volt_data *omap_voltage_get_voltdata(struct voltagedomain *voltdm,
 {
 	int i;
 
-	if (!voltdm || IS_ERR(voltdm)) {
+	if (IS_ERR_OR_NULL(voltdm)) {
 		pr_warn("%s: VDD specified does not exist!\n", __func__);
 		return ERR_PTR(-EINVAL);
 	}
@@ -216,7 +216,7 @@ struct omap_volt_data *omap_voltage_get_voltdata(struct voltagedomain *voltdm,
 int omap_voltage_register_pmic(struct voltagedomain *voltdm,
 			       struct omap_voltdm_pmic *pmic)
 {
-	if (!voltdm || IS_ERR(voltdm)) {
+	if (IS_ERR_OR_NULL(voltdm)) {
 		pr_warn("%s: VDD specified does not exist!\n", __func__);
 		return -EINVAL;
 	}

arch/arm/mach-omap2/vp.c

@@ -199,7 +199,7 @@ void omap_vp_enable(struct voltagedomain *voltdm)
 	struct omap_vp_instance *vp;
 	u32 vpconfig, volt;
 
-	if (!voltdm || IS_ERR(voltdm)) {
+	if (IS_ERR_OR_NULL(voltdm)) {
 		pr_warn("%s: VDD specified does not exist!\n", __func__);
 		return;
 	}
@@ -244,7 +244,7 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 	u32 vpconfig;
 	int timeout;
 
-	if (!voltdm || IS_ERR(voltdm)) {
+	if (IS_ERR_OR_NULL(voltdm)) {
 		pr_warn("%s: VDD specified does not exist!\n", __func__);
 		return;
 	}