video: fbdev: Use IS_BUILTIN

IS_BUILTIN can be use to replace various initializations
like #if CONFIG_<FOO> int val = 1; #else int val = 0; #endif
so do so.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b1cf967015c5beafa475aaa30d8e21a58caff870.camel@perches.com