net/mlx5e: TC, Split pedit offloads verify from alloc_tc_pedit_action()

Split pedit verify part into a new subfunction for better
maintainability.

Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>