rt8821ae: fix introduced bugs

Fixes bugs introduced by 65d2c74355a5c74e3fabccd79891b4b960b2a1f6
commit, my fault.

o ether_addr_equal() returns 0 when addrs match.
  Fix done by Troy Tan <troy_tan@realsil.com.cn>
o WIPHY_FLAG_* leaves intact (may be useful for ppl running old kernels)