octeontx2-pf: Fix ethtool support for SDP representors

The hardware supports multiple MAC types, including RPM, SDP, and LBK.
However, features such as link settings and pause frames are only available
on RPM MAC, and not supported on SDP or LBK.

This patch updates the ethtool operations logic accordingly to reflect
this behavior.

Fixes: 2f7f33a0 ("octeontx2-pf: Add representors for sdp MAC")
Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>