fbdev: do not let CONFIG_FB_DEFERRED_IO default to y

CONFIG_FB_DEFERRED_IO can not be turned off, while it's already selected
automatically by the drivers that need it.

Although it's nice to have more compile-coverage, not being able to disable a
rarely used feature is annoying.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Acked-by: Jaya Kumar <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/video/Kconfig

···
 config FB_DEFERRED_IO
 	bool
 	depends on FB
-	default y
 
 config FB_METRONOME
 	tristate