net: ethernet: ti: icssg_prueth: extend multiq support for SR1

SR1 ICSSG firmware support 3 Egress data channels and 1 management
channel. So extend the multiq support for SR1 and implement 3
hwqueues at the Egress. Management channel number used is highest
data channel number + 1. Ethtool -l command will show maximum
of 3 hwqueues for Egress that can be configured by user.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Acked-by: Roger Quadros <rogerq@ti.com>