usb: gadget: remove gadget_chips.h

This header file contains helpers for quirks based on UDC controller name.
Since we have generic quirk bitfields in usb_gadget structure for all of
these quirks we don't need to have this header any longer.

This patch removes gadget_chips.h file and makes sure that it's no longer
included anywhere in kernel sources.

Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>