phy: renesas: rcar-gen3-usb2: Rename has_otg_pins to uses_otg_pins

Since R-Car E3 and D3 have dedicated otg pins actually, "has_otg_pins"
is possible to misread in the future. So, this patch renames
has_otg_pins to uses_otg_pins.

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>