Revert "msm: vidc: Do not fail registration if buffer is already registered"

This reverts commit 2e527a0d ("msm: vidc: Do not fail registration
if buffer is already registered")

The change being reverted caused power regression. Reverting
the change does not break ROI feature (for which the change was
initially made).

Change-Id: Ia22ec87ac0a85c858058a3da56e4709d0b1841ff
Signed-off-by: Vinay Kalia <vkalia@codeaurora.org>