staging: brcm80211: Fix debug section mismatch warning

wl_remove() is now called from places other than the .remove field of struct pci_driver so
do not annotate wl_remove() with __devexit.  This removes the debug section mismatch warning
introduced by the previous nonexistant firmware patch.

Signed-off-by: Brett Rudley <brudley@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>