ocxl: Fix missing unlock on error in afu_ioctl_enable_p9_wait()

ocxl: Fix missing unlock on error in afu_ioctl_enable_p9_wait()

BugLink: http://bugs.launchpad.net/bugs/1775786
Add the missing unlock before return from function
afu_ioctl_enable_p9_wait() in the error handling case.

Fixes: e948e06fc63a ("ocxl: Expose the thread_id needed for wait on POWER9")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Alastair D'Silva <alastair@d-silva.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit 2e5c93d6bb2f7bc17eb82748943a1b9f6b068520)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>