qede: Decouple ethtool caps from qed

While the qed_lm_maps is closely tied with the QED_LM_* defines,
when iterating over the array use actual size instead of the qed
define to prevent future possible issues.

Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>