usb: Makefile: fix drivers/usb/phy/ Makefile entry

drivers/usb/phy/ should be compiled everytime
we have CONFIG_USB_OTG_UTILS enabled.

phy/ should've been part of the build process based
on CONFIG_USB_OTG_UTILS, don't know where I had my head
when I allowed CONFIG_USB_COMMON there.

In fact commit c6156328
tried to fix a previous issue but it made things even
worse.

The real solution is to compile phy/ based on
CONFIG_USB_OTG_UTILS which gets selected by all PHY
drivers.

I only triggered the error recently after accepting a
patch which moved a bunch of code from otg/otg.c to
phy/phy.c and running 100 randconfig cycles.
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/Makefile

@@ -46,7 +46,7 @@ obj-$(CONFIG_USB_MICROTEK)	+= image/
 obj-$(CONFIG_USB_SERIAL)	+= serial/
 
 obj-$(CONFIG_USB)		+= misc/
-obj-$(CONFIG_USB_COMMON)	+= phy/
+obj-$(CONFIG_USB_OTG_UTILS)	+= phy/
 obj-$(CONFIG_EARLY_PRINTK_DBGP)	+= early/
 
 obj-$(CONFIG_USB_ATM)		+= atm/