IOCTL: Unlock before freeing memory if transaction submission failed

Since transaction submission failed, the transaction data struct will
not be used by any other blocks anymore. It is safe to first release the
spinlock, then copy to user and release the memory.

Bug: 197431438
Test: CTS and GCA
Signed-off-by: Edmond Chung <edmondchung@google.com>
Change-Id: I1054d0591b6ca55ae7d192b46e535a1ae0fdde00