RDMA/bnxt_re: Fix incorrect DB offset calculation

[ Upstream commit c354dff00db8df80f271418d8392065e10ffffb6 ]

To support host systems with non 4K page size, l2_db_size shall be
calculated with 4096 instead of PAGE_SIZE. Also, supply the host page size
to FW during initialization.

Signed-off-by: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>