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: e86d69dd ("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.orgSigned-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>