net/mlx5e: Add missing support for PTP_CLK_REQ_PPS request

Add the missing option to enable the PTP_CLK_PPS function.
In this case pin should be configured as 1PPS IN first and
then it will be connected to PPS mechanism.
Events will be reported as PTP_CLOCK_PPSUSR events to relevant sysfs.

Fixes: ee7f1220 ('net/mlx5e: Implement 1PPS support')
Signed-off-by: Eugenia Emantayev <eugenia@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>