staging: r8712u: Fix regression caused by commit 8c213fa

commit 2080913e017ab9f88379d93fd09546ad95faf87b upstream.

In commit 8c213fa "staging: r8712u: Use asynchronous firmware loading",
the command to release the firmware was placed in the wrong routine.

In combination with the bug introduced in commit a5ee652 "staging: r8712u:
Interface-state not fully tracked", the driver attempts to upload firmware
that had already been released. This bug is the source of one of the
problems in https://bugs.archlinux.org/task/27996#comment89833.

Tested-by: Alberto Lago Ballesteros <saniukeokusainaya@gmail.com>
Tested-by: Adrian <agib@gmx.de>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>