msm: ADSPRPC: Call free only when allocation succeed

Call free only when allocation succeeded, otherwise skip freeing
remote heap memory.

Change-Id: I749c7956377764fe04e1b47898b4acb390c6b942
Acked-by: Himateja Reddy <hmreddy@qti.qualcomm.com>
Signed-off-by: Sathish Ambley <sathishambley@codeaurora.org>