[media] omap3isp: Fix compilation error in ispreg.h

Commit c49f34bc ("ARM: OMAP2+ Move SoC specific headers to be local to
mach-omap2") moved omap34xx.h to mach-omap2. This broke omap3isp, as it
includes omap34xx.h.
Instead of moving omap34xx to platform_data, simply add the two
definitions the driver needs and remove the include altogether.

Signed-off-by: Ido Yariv <ido@wizery.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>