regulator: lp872x: make a const array static, makes object smaller

Don't populate const array lp872x_num_regulators  on the stack but
instead make it static. Makes the object code smaller by 29 bytes.

Before:
   text	   data	    bss	    dec	    hex	filename
  18441	   4624	     64	  23129	   5a59	drivers/regulator/lp872x.o

After:
   text	   data	    bss	    dec	    hex	filename
  18316	   4720	     64	  23100	   5a3c	drivers/regulator/lp872x.o

(gcc version 10.2.0)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20201016222235.686981-1-colin.king@canonical.com
Signed-off-by: Mark Brown <broonie@kernel.org>