power: rt9455: hide unused rt9455_boost_voltage_values

The rt9455_boost_voltage_values[] array is only used when USB PHY
support is enabled, causing a W=1 warning otherwise:

drivers/power/supply/rt9455_charger.c:200:18: error: 'rt9455_boost_voltage_values' defined but not used [-Werror=unused-const-variable=]

Enclose the definition in the same #ifdef as the references to it.

Fixes: e86d69d ("power_supply: Add support for Richtek RT9455 battery charger")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20240403080702.3509288-10-arnd@kernel.org
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/rt9455_charger.c

@@ -192,6 +192,7 @@ static const int rt9455_voreg_values[] = {
 	4450000, 4450000, 4450000, 4450000, 4450000, 4450000, 4450000, 4450000
 };
 
+#if IS_ENABLED(CONFIG_USB_PHY)
 /*
  * When the charger is in boost mode, REG02[7:2] represent boost output
  * voltage.
@@ -207,6 +208,7 @@ static const int rt9455_boost_voltage_values[] = {
 	5600000, 5600000, 5600000, 5600000, 5600000, 5600000, 5600000, 5600000,
 	5600000, 5600000, 5600000, 5600000, 5600000, 5600000, 5600000, 5600000,
 };
+#endif
 
 /* REG07[3:0] (VMREG) in uV */
 static const int rt9455_vmreg_values[] = {