usb: chipidea: usbmisc_imx: fix returnvar.cocci warnings

drivers/usb/chipidea/usbmisc_imx.c:277:5-8: Unneeded variable: "ret". Return "0" on line 297

 Removes unneeded variable used to store return value.

Generated by: scripts/coccinelle/misc/returnvar.cocci

Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>