media: ov9640: make const arrays res_x/y static const, reduces object code size

Don't populate the arrays res_x and resy_y on the stack, instead make them
static const.  Makes the object code smaller by over 160 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
  10509	   2800	     64	  13373	   343d	ov9640.o

After:
   text	   data	    bss	    dec	    hex	filename
  10184	   2960	     64	  13208	   3398	ov9640.o

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>