regulator: rpi-panel-v2: Fix missing OF dependency

Add missing OF dependency and drop of_match_ptr() use.
This fixes the following LKP report:

"
>> drivers/regulator/rpi-panel-v2-regulator.c:95:34: warning: 'rpi_panel_v2_dt_ids' defined but not used [-Wunused-const-variable=]
    static const struct of_device_id rpi_panel_v2_dt_ids[] = {
                                     ^~~~~~~~~~~~~~~~~~~
"

Fixes: d493058 ("regulator: rpi-panel-v2: Add regulator for 7" Raspberry Pi 720x1280")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202506100440.fyTGO7CG-lkp@intel.com/
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Link: https://patch.msgid.link/20250609223012.87764-1-marek.vasut+renesas@mailbox.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Marek Vasut

drivers/regulator/Kconfig

@@ -1156,7 +1156,7 @@ config REGULATOR_RASPBERRYPI_TOUCHSCREEN_ATTINY
 config REGULATOR_RASPBERRYPI_TOUCHSCREEN_V2
 	tristate "Raspberry Pi 7-inch touchscreen panel V2 regulator"
 	depends on GPIOLIB
-	depends on I2C
+	depends on I2C && OF
 	select GPIO_REGMAP
 	select REGMAP_I2C
 	help

drivers/regulator/rpi-panel-v2-regulator.c

@@ -102,7 +102,7 @@ static struct i2c_driver rpi_panel_v2_regulator_driver = {
 	.driver = {
 		.name = "rpi_touchscreen_v2",
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
-		.of_match_table = of_match_ptr(rpi_panel_v2_dt_ids),
+		.of_match_table = rpi_panel_v2_dt_ids,
 	},
 	.probe = rpi_panel_v2_i2c_probe,
 };