Revert "msm: vidc: cache-invalidate encoder output buffers after alloc"

This reverts commit 00acad4065e81cb19a9a270cac2ff496ce57ea63, since
change I3f2c9b7c13b3e09097ce07ca7b59154b97401052 removed buffer
kernel mapping entirely, causing this to operate on non-existing
buffers

Change-Id: I353ebe42afe026530527f3c7c9d2053ff53e8c6f