usb: gadget: amd5536udc: fix spelling mistake "reserverd" -> "reserved"

The variable is named reserved, the comment should say so.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200214142446.22483-1-alexandre.belloni@bootlin.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>