regulator: scmi: Use int type to store negative error codes

Change the 'ret' variable from u32 to int to store negative error codes or
zero returned by of_property_read_u32().

Storing the negative error codes in unsigned type, doesn't cause an issue
at runtime but it's ugly as pants. Additionally, assigning negative error
codes to unsigned type may trigger a GCC warning when the -Wsign-conversion
flag is enabled.

No effect on runtime.

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Fixes: 0fbeae7 ("regulator: add SCMI driver")
Link: https://patch.msgid.link/20250829101411.625214-1-rongqianfeng@vivo.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: qianfengrong

drivers/regulator/scmi-regulator.c

@@ -257,7 +257,8 @@ static int process_scmi_regulator_of_node(struct scmi_device *sdev,
 					  struct device_node *np,
 					  struct scmi_regulator_info *rinfo)
 {
-	u32 dom, ret;
+	u32 dom;
+	int ret;
 
 	ret = of_property_read_u32(np, "reg", &dom);
 	if (ret)