usb: dwc2: Do not set host parameter in peripheral mode

Since commit "usb: dwc2: Improve handling of host and device hwparams" the
host mode specific hardware parameter aren't initialized in peripheral mode
from the register settings anymore. So we better do not set them in this
case which avoids the following warnings on bcm2835:

  256 invalid for host_nperio_tx_fifo_size. Check HW configuration.
  512 invalid for host_perio_tx_fifo_size. Check HW configuration.

Fixes: 55e1040e ("usb: dwc2: Improve handling of host and device hwparams")
Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>