net/mlx5e: Use inline MTTs in UMR WQEs

When modifying the page mapping of a HW memory region
(via a UMR post), post the new values inlined in WQE,
instead of using a data pointer.

This is a micro-optimization, inline UMR WQEs of different
rings scale better in HW.

In addition, this obsoletes a few control flows and helps
delete ~50 LOC.

Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>