usb: renesas_usbhs: disable TX IRQ before starting TX DMAC transfer

commit 6490865c upstream.

This patch adds a code to surely disable TX IRQ of the pipe before
starting TX DMAC transfer. Otherwise, a lot of unnecessary TX IRQs
may happen in rare cases when DMAC is used.

Fixes: e73a9891 ("usb: renesas_usbhs: add DMAEngine support")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>