usb: musb-new: sunxi: remove unused define

This is a remnant from when the USB controller driver managed
the reset signal itself. A patch from the very end of 2018 changed
this driver to delegate reset (and clock) management to the proper
control unit driver, but left this unused define behind.

Signed-off-by: Sam Edwards <CFSworks@gmail.com>
Reviewed-by: Marek Vasut <marex@denx.de>