usb: phy: move all PHY drivers to drivers/usb/phy/

that's a much more reasonable location for
those drivers. It helps us saving drivers/usb/otg/
for when we actually start adding generic OTG
code.

Also completely delete drivers/usb/otg/ as there's
nothing left there.

Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/Makefile

@@ -6,8 +6,6 @@
 
 obj-$(CONFIG_USB)		+= core/
 
-obj-$(CONFIG_USB_OTG_UTILS)	+= otg/
-
 obj-$(CONFIG_USB_DWC3)		+= dwc3/
 
 obj-$(CONFIG_USB_MON)		+= mon/