crypto/NX: Set receive window credits to max number of CRBs in RxFIFO

commit e52d484d9869eb291140545746ccbe5ffc7c9306 upstream.

System gets checkstop if RxFIFO overruns with more requests than the
maximum possible number of CRBs in FIFO at the same time. The max number
of requests per window is controlled by window credits. So find max
CRBs from FIFO size and set it to receive window credits.

Fixes: b0d6c9ba ("crypto/nx: Add P9 NX support for 842 compression engine")
CC: stable@vger.kernel.org # v4.14+
Signed-off-by: Haren Myneni <haren@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>