pvrdma: check number of pages when creating rings

pvrdma: check number of pages when creating rings

When creating CQ/QP rings, an object can have up to
PVRDMA_MAX_FAST_REG_PAGES 8 pages. Check 'npages' parameter
to avoid excessive memory allocation or a null dereference.

Reported-by: Li Qiang <liq3ea@163.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
(cherry picked from commit 2c858ce5da8ae6689c75182b73bc455a291cad41)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>