usb: renesas_usbhs: fix usbhs_pipe_clear() for DCP PIPE

Since the DCPCTR doesn't have the ACLRM bit, the usbus_pipe_clear()
should not call the usbhsp_pipectrl_set() with ACLRM.
So, this patch fixes this issue to add the usbhs_fifo_clear_dcp()
in fifo.c because the controller needs the CFIFO to clear the
the DCP PIPE.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>