Revert "mwifiex: cancel cmd timer and free curr_cmd in shutdown process

revert commit b9f1f48ce20a1b923429c216669d03b5a900a8cf which is commit
084c7189acb3f969c855536166042e27f5dd703f upstream.

It shouldn't have been applied to the 3.4-stable tree.

Reported-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Marco Cesarano <marco@marvell.com>
Reported-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>