msm: ocmem: Serialize allocation requests only when necessary

Certain clients of ocmem always have exclusive regions set aside in
the OCMEM memory map. Allocation requests for such clients do not
have to wait for any pending evictions in progress to be completed
nor will trigger any new evictions and can be safely scheduled right
away.

Signed-off-by: Naveen Ramaraj <nramaraj@codeaurora.org>
Signed-off-by: Neeti Desai <neetid@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>