qlnxe: Fix advertising the IFCAP_LINKSTATE capability

The following up advertising of IFCAP_HWCSUM capability unconditionally
overwrite IFCAP_LINKSTATE.

Reviewed by: kbowling
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D51450

(cherry picked from commit c18860339d5051dea99cb5cee7e322ffa5dd2a81)