usb: renesas_usbhs: remove controlling PWEN/EXTLP support

Controlling PWMEN/EXTLP (named as "has_otg") was supported in v3.2,
but the last user (kzm9g) was removed by the commit 30f8925a


("ARM: shmobile: Remove legacy board code for KZM-A9-GT"). So, this
patch remove it.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>