msm: ADSPRPC: Add exec permission for hyp_assign_phys

Add execute permission for hyp_assign_phys for adsp shared
memory region to allow for the memory to be reused by other user
space processes when this is not used by the remote processor.

Change-Id: I4a116dfdad85b57f0706a9480b3eb1c09f079dbb
Acked-by: Viswanatham Paduchuri <vpaduchu@qti.qualcomm.com>
Signed-off-by: Sathish Ambley <sathishambley@codeaurora.org>