regulator: raa215300: Change the scope of the variables {clkin_name, xin_name}

regulator: raa215300: Change the scope of the variables {clkin_name, xin_name}

Change the scope of the variables {clkin_name, xin_name} from global->local
to fix the below warning.

drivers/regulator/raa215300.c:42:12: sparse: sparse: symbol 'xin_name' was
not declared. Should it be static?

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202306250552.Fan9WTiN-lkp@intel.com/
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230629104200.102663-1-biju.das.jz@bp.renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>