misc: fastrpc: Unmap only if buffer is unmapped from DSP

misc: fastrpc: Unmap only if buffer is unmapped from DSP

commit 509143385db364c67556a914bef6c9a42fd2c74c upstream.

For unmapping any buffer from kernel, it should first be unmapped
from DSP. In case unmap from DSP request fails, the map should not
be removed from kernel as it might lead to SMMU faults and other
memory issues.

Fixes: 5c1b97c7d7b7 ("misc: fastrpc: add support for FASTRPC_IOCTL_MEM_MAP/UNMAP")
Cc: stable <stable@kernel.org>
Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20231013122007.174464-5-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>