msm: adsprpc: Handle hyp assign errors properly for dsp

In case of hyp assign error ,if process group mmap passed,
do process group unmap too so that mapping on dsp is also
removed.

Change-Id: Ibd5cf783baee0476e6b687631ccbf132deaa847a
Acked-by: Deepika Singh <dsi@qti.qualcomm.com>
Signed-off-by: Mohammed Nayeem Ur Rahman <mohara@codeaurora.org>