Add usb: dwc2: fix regression on big-endian PowerPC/ARM systems for 4.4+

Hello stable-team,

I would like to propose the following patch to be included in -stable for 4.4:

Subject: usb: dwc2: fix regression on big-endian PowerPC/ARM systems
Commit ID: 23e3439296a55affce3ef0ab78f1c2e03aec8767 [0]

This patch fixes an regression which was introduced by:
"usb: dwc2: Use platform endianness when accessing registers".
It broke the DWC2 USB gadget/host controller on big-endian
systems like APM82181 (PowerPC-SoC) and possibly big-endian
ARM systems.

Regards,
Christian 

[0] <https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=23e3439296a55affce3ef0ab78f1c2e03aec8767>