drm: armada: constify drm_prop_enum_list structures.

drm_prop_enum_lists are not supposed to change at runtime. All functions
working with drm_prop_enum_list provided by <drm/drm_property.h> work
with
const drm_prop_enum_list. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   9629	    744	      0	  10373	   2885 drivers/gpu/drm/armada/armada_crtc.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   9757	    616	      0	  10373	   2885 drivers/gpu/drm/armada/armada_crtc.o

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/d2344c4dc40238cfe48fa6d917767df0f053150a.1498902844.git.arvind.yadav.cs@gmail.com

drivers/gpu/drm/armada/armada_crtc.c

@@ -1150,13 +1150,13 @@ int armada_drm_plane_init(struct armada_plane *plane)
 	return 0;
 }
 
-static struct drm_prop_enum_list armada_drm_csc_yuv_enum_list[] = {
+static const struct drm_prop_enum_list armada_drm_csc_yuv_enum_list[] = {
 	{ CSC_AUTO,        "Auto" },
 	{ CSC_YUV_CCIR601, "CCIR601" },
 	{ CSC_YUV_CCIR709, "CCIR709" },
 };
 
-static struct drm_prop_enum_list armada_drm_csc_rgb_enum_list[] = {
+static const struct drm_prop_enum_list armada_drm_csc_rgb_enum_list[] = {
 	{ CSC_AUTO,         "Auto" },
 	{ CSC_RGB_COMPUTER, "Computer system" },
 	{ CSC_RGB_STUDIO,   "Studio" },