backlight: aw99706: Fix unused function warnings from suspend/resume ops

When building for a platform without CONFIG_PM_SLEEP, such as s390,
there are two unused function warnings:

  drivers/video/backlight/aw99706.c:436:12: error: 'aw99706_resume' defined but not used [-Werror=unused-function]
    436 | static int aw99706_resume(struct device *dev)
        |            ^~~~~~~~~~~~~~
  drivers/video/backlight/aw99706.c:429:12: error: 'aw99706_suspend' defined but not used [-Werror=unused-function]
    429 | static int aw99706_suspend(struct device *dev)
        |            ^~~~~~~~~~~~~~~

SET_SYSTEM_SLEEP_PM_OPS, used within SIMPLE_DEV_PM_OPS, expands to
nothing when CONFIG_PM_SLEEP is not set, so these functions are
completely unused in this configuration.

SIMPLE_DEV_PM_OPS is deprecated in favor of DEFINE_SIMPLE_DEV_PM_OPS,
which avoids this issue by using pm_sleep_ptr to make these callbacks
NULL when CONFIG_PM_SLEEP is unset while making the callback functions
always appear used to the compiler regardless of configuration. Switch
to DEFINE_SIMPLE_DEV_PM_OPS for aw99706_pm_ops to clear up the warning.

Additionally, wrap the pointer to aw99706_pm_ops in pm_ptr() in
aw99706_i2c_driver to ensure that the structure is completely eliminated
in configurations without CONFIG_PM.

Fixes: 88a8e9b ("backlight: aw99706: Add support for Awinic AW99706 backlight")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20251120-backlight-aw99706-fix-unused-pm-functions-v1-1-8b9c17c4e783@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

Author: nathanchance

drivers/video/backlight/aw99706.c

@@ -440,7 +440,7 @@ static int aw99706_resume(struct device *dev)
 	return aw99706_hw_init(aw);
 }
 
-static SIMPLE_DEV_PM_OPS(aw99706_pm_ops, aw99706_suspend, aw99706_resume);
+static DEFINE_SIMPLE_DEV_PM_OPS(aw99706_pm_ops, aw99706_suspend, aw99706_resume);
 
 static const struct i2c_device_id aw99706_ids[] = {
 	{ "aw99706" },
@@ -461,7 +461,7 @@ static struct i2c_driver aw99706_i2c_driver = {
 	.driver = {
 		.name = "aw99706",
 		.of_match_table = aw99706_match_table,
-		.pm = &aw99706_pm_ops,
+		.pm = pm_ptr(&aw99706_pm_ops),
 	},
 };