qlnxe: Remove a pointless copy back from the link-layer address

On ifnet attaching, ether_ifattach() makes the link-layer address by
shadow copying the ha->primary_mac. Well, the link-layer address will
not be altered during attaching, thus it is pointless to copy it back.

No functional change intended.

Reviewed by: kbowling
MFC after: 5 days
Differential Revision: https://reviews.freebsd.org/D54883

(cherry picked from commit 4ac3081b282800158df7abe93f307d76e1b5b808)
(cherry picked from commit 23ffd1650cc431e762387d384ede99ae085bc130)
(cherry picked from commit 7d7cee09b9a4ac5cbcbac79cb7ccfef5d6db1e0f)