This is a specific implementation, <asm/unaligned.h> is the
multiplexer that has the arch-specific knowledge of which
of the implementations needs to be used, so include that.

This issue was revealed by kbuild testing
when <asm/unaligned.h> was added in <linux/ieee80211.h>
resulting in redefinition of get_unaligned_be16 (and
probably others).

Cc: stable@vger.kernel.org # v3.17
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NArend van Spriel <arend@broadcom.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>