USB: gadget: Add i.MX3x support to the fsl_usb2_udc driver

This patch adds support for i.MX3x (only tested with i.MX31 so far) ARM
SoCs to the fsl_usb2_udc driver. It also moves PHY configuration before
controller reset, because otherwise an ULPI PHY doesn't get a reset and
doesn't function after a reboot. The problem with longer control transfers
is still not fixed. The patch renames the fsl_usb2_udc.c file to
fsl_udc_core.c to preserve the same module name for user-space
backwards compatibility.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>