media: drxd: make const arrays slowIncrDecLUT and fastIncrDecLUT static

Don't populate arrays slowIncrDecLUT and fastIncrDecLUT on the stack but
instead make them static. Makes the object code smaller by over 100 bytes:

   text	   data	    bss	    dec	    hex	filename
  27776	    832	     64	  28672	   7000	drxd_hard.o

   text	   data	    bss	    dec	    hex	filename
  27530	    976	     64	  28570	   6f9a	drxd_hard.o

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