msm: vidc: Skip validating buffer counts in close

No need to validate the buffer counts while closing the
session because close may be called before buffer counts
are finalized where validation fails.

CRs-Fixed: 2132919
Change-Id: I239981c24feb01d36850b32bf2eefed7f2d10230
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>