msm: kgsl: Correct memdesc conditions in cma_coherent_free

The condition in question simply OR'd memdesc->priv and hence
always evaluated to be true. Change the conditional operator to &
to fix this since it would break NOMMU mode. Also fix the condition
one level below.

Change-Id: Id02404cea01174a1be276fe164f757103a25ed49
Signed-off-by: Shrenuj Bansal <shrenujb@codeaurora.org>