net/mlx5e: Validate stop_room size upon user input

net/mlx5e: Validate stop_room size upon user input

Stop room is a space that may be taken by WQEs in the SQ during a packet
transmit. It is used to check if next packet has enough room in the SQ.
Stop room guarantees this packet can be served and if not, the queue is
stopped, so no more packets are passed to the driver until it's ready.

Currently, stop_room size is calculated and validated upon tx queues
allocation. This makes it impossible to know if user provided valid
input for certain parameters when interface is down.

Instead, store stop_room in mlx5e_sq_param and create
mlx5e_validate_params(), to validate its fields upon user input even
when the interface is down.

Signed-off-by: Vladyslav Tarasiuk <vladyslavt@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>