RDMA/bnxt_re: Correct FRMR size calculation

FRMR WQE requires to provide the log2 value of the PBL and page size.  Use
the standard ilog2() to calculate the log2 value

Link: https://lore.kernel.org/r/1631709163-2287-11-git-send-email-selvin.xavier@broadcom.com


Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>