OMAP: OMAPFB: disable old omapfb for OMAP4 builds

Build fails when OMAP4 and FB_OMAP are defined:

drivers/built-in.o: In function `omapfb_do_probe':
drivers/video/omap/omapfb_main.c:1773: undefined reference to `omap2_int_ctrl'

Old omapfb does not work on OMAP4, and never will. Change the omapfb
build dependency so that old omapfb depends on OMAP1/2/3, fixing the
build for plain OMAP4 builds.

Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>