drm/omap: fbdev: avoid double initializer entry

Fix sparse warning:

drivers/gpu/drm/omapdrm/omap_fbdev.c:83:9: warning: Initializer entry defined twice
drivers/gpu/drm/omapdrm/omap_fbdev.c:91:10:   also defined here

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>