RDMA/mlx5: Fix page size bitmap calculation for KSM mode

RDMA/mlx5: Fix page size bitmap calculation for KSM mode

When using KSM (Key Scatter-gather Memory) access mode, the HW requires
the IOVA to be aligned to the selected page size.
Without this alignment, the HW may not function correctly.

Currently, mlx5_umem_mkc_find_best_pgsz() does not filter out page sizes
that would result in misaligned IOVAs for KSM mode. This can lead to
selecting page sizes that are incompatible with the given IOVA.

Fix this by filtering the page size bitmap when in KSM mode, keeping
only page sizes to which the IOVA is aligned to.

Fixes: fcfb03597b7d ("RDMA/mlx5: Align mkc page size capability check to PRM")
Signed-off-by: Edward Srouji <edwards@nvidia.com>
Link: https://patch.msgid.link/20250824144839.154717-1-edwards@nvidia.com
Reviewed-by: Michael Guralnik <michaelgur@nvidia.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>