crypto: caam - fix signals handling

commit 7459e1d25ffefa2b1be799477fcc1f6c62f6cec7 upstream.

Driver does not properly handle the case when signals interrupt
wait_for_completion_interruptible():
-it does not check for return value
-completion structure is allocated on stack; in case a signal interrupts
the sleep, it will go out of scope, causing the worker thread
(caam_jr_dequeue) to fail when it accesses it

wait_for_completion_interruptible() is replaced with uninterruptable
wait_for_completion().
We choose to block all signals while waiting for I/O (device executing
the split key generation job descriptor) since the alternative - in
order to have a deterministic device state - would be to flush the job
ring (aborting *all* in-progress jobs).

Fixes: 045e3678 ("crypto: caam - ahash hmac support")
Fixes: 4c1ec1f9 ("crypto: caam - refactor key_gen, sg")
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>