usb: renesas_usbhs: set the mode by using extcon state for non-otg channel

The usbhs_rcar3_power_and_pll_ctrl() will be used by non-otg channel
(e.g. R-Car D3) and the previous code has hardcoded as peripheral mode.
So, this patch sets the mode by using extcon state.
If the channel doesn't get any extcon devices, this driver's behavior
is the same as before.

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