Don't populate the const array func_base on the stack but instead it
static. Makes the object code smaller by 55 bytes:

Before:
   text    data     bss     dec    hex filename
   6422    3216      64    9702   25e6 drivers/regulator/rt6245-regulator.o

After:
   text    data     bss     dec    hex filename
   6303    3280      64    9647   25af drivers/regulator/rt6245-regulator.o

Reduction of 55 bytes

(gcc version 10.3.0)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210715141531.27672-1-colin.king@canonical.comSigned-off-by: Mark Brown <broonie@kernel.org>