platform/x86: int3472/discrete: set variable skl_int3472_regulator_second_sensor...

platform/x86: int3472/discrete: set variable skl_int3472_regulator_second_sensor storage-class-specifier to static

smatch reports
drivers/platform/x86/intel/int3472/clk_and_regulator.c:263:28: warning: symbol
  'skl_int3472_regulator_second_sensor' was not declared. Should it be static?

This variable is only used in its defining file, so it should be static.

Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20230702134419.3438361-1-trix@redhat.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>