OMAPDSS: VENC: Remove cpu_is_xxxx checks

OMAP4 checks are removed from VENC to provide it a cleaner interface. These
checks were introduced by patches "HACK: OMAP: DSS2: VENC: disable VENC on OMAP4
to prevent crash" (ba02fa37) by Tomi Valkeinen <tomi.valkeinen@ti.com> and
"OMAPDSS: VENC: fix NULL pointer dereference in DSS2 VENC sysfs debug attr on
OMAP4" (cc1d3e03

)  by Danny Kukawka <danny.kukawka@bisect.de> to prevent VENC
from crashing OMAP4 kernel.

Signed-off-by: Chandrabhanu Mahapatra <cmahapatra@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>