usb: gadget: lpc32xxx_udc: clean up and sort include directives out

Remove mach/irq.h from the list of included headers, there is no
compilation dependency on this include file, and the change is needed
to prevent a compilation failure, when mach/irq.h is removed.

Additionally remove other unneeded includes and sort out their order.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>