phy: renesas: rcar-gen3-usb2: add conditions for uses_otg_pins == false

If uses_otg_pins is set to false, this driver 1) should disable otg
related interruptions, and 2) should not get ID pin signal, to avoid
unexpected behaviors. So, this patch adds conditions for it.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>