arch: Select fbdev helpers with CONFIG_VIDEO

Various Kconfig options selected the per-architecture helpers for
fbdev. But none of the contained code depends on fbdev. Standardize
on CONFIG_VIDEO, which will allow to add more general helpers for
video functionality.

CONFIG_VIDEO protects each architecture's video/ directory. This
allows for the use of more fine-grained control for each directory's
files, such as the use of CONFIG_STI_CORE on parisc.

v2:
- sparc: rebased onto Makefile changes

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>