Input: walkera0701 - fix crash on startup

commit a455e2985f57e2a71566bb8850094af38b2c932d upstream.

The driver's timer must be set up before enabling IRQ handler, otherwise
bad things may happen.

Reported-and-tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Popovec <popovec@fei.tuke.sk>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>