wl1251: fix crash on remove due to premature kfree

wl1251: fix crash on remove due to premature kfree

commit 328c32f0f85467af5a6c4c3289e168d9ad2555af upstream.

Currently SDIO glue frees it's own structure before calling
wl1251_free_hw(), which in turn calls ieee80211_unregister_hw().
The later call may result in a need to communicate with the chip
to stop it (as it happens now if the interface is still up before
rmmod), which means calls are made back to the glue, resulting in
freed memory access.

Fix this by freeing glue data last.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>