fbdev: omap2: omapfb: fix boolreturn.cocci warnings

drivers/video/fbdev/omap2/omapfb/omapfb-main.c:290:9-10: WARNING: return of 0/1 in function 'cmp_var_to_colormode' with return type bool

 Return statements in functions returning bool should use
 true/false instead of 1/0.
Generated by: scripts/coccinelle/misc/boolreturn.cocci

Fixes: 7378f114 ("media: omap2: omapfb: allow building it with COMPILE_TEST")
Signed-off-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Mauro Carvalho Chehab <m.chehab@samsung.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>