staging: r8188eu: replace a get_da call

The r8188eu driver implements an internal get_da function to read the
destination address (da) from an incoming message. Callers of this
function should be updated to use the ieee80211 framework, with the goal
of removing get_da eventually.

This patch replaces a get_da call in the OnAssocRsp function.

Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220806111352.690650-2-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>