usb: renesas_usbhs: remove redundant polling in usbhsf_fifo_barrier()

The datasheet doesn't mention that needs to poll of FRDY is set or not.
So, this patch removes such handling in the usbhsf_fifo_barrier().

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