usb: musb: Make musb_write_rxfun* and musb_write_rxhub* work like their tx versions

For some reason the musb_write_rxfun* and musb_write_rxhub* functions had
a different function prototype and some extra magic needed on the caller side
compared to their tx counterparts, this commit makes them work the same as
their tx counterparts.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>