The WEXT ioctl SIOCSIWRATE is not implemented in mac80211. This patch
adds the missing routine. It supports the 'auto' keyword, fixed rates,
and the combination of 'auto' and a fixed rate to select an upper bound.

Based on the patch from Mohamed Abbas <mabbas@linux.intel.com>.
Signed-off-by: NLarry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: NJiri Benc <jbenc@suse.cz>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>