usb: kconfig: fix warning of select USB_OTG

When choose randconfig for kernel build, it reports below warning:
"warning: (USB_OTG_FSM && FSL_USB2_OTG && USB_MV_OTG) selects USB_OTG
which has unmet direct dependencies (USB_SUPPORT && USB && PM)"

In fact, USB_OTG is visible symbol and depends on PM, so the driver
needs to depend on it to reduce dependency problem.

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Cc: Felipe Balbi <balbi@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/core/Kconfig

@@ -77,8 +77,7 @@ config USB_OTG_BLACKLIST_HUB
 
 config USB_OTG_FSM
 	tristate "USB 2.0 OTG FSM implementation"
-	depends on USB
-	select USB_OTG
+	depends on USB && USB_OTG
 	select USB_PHY
 	help
 	  Implements OTG Finite State Machine as specified in On-The-Go

drivers/usb/phy/Kconfig

@@ -21,7 +21,6 @@ config AB8500_USB
 config FSL_USB2_OTG
 	bool "Freescale USB OTG Transceiver Driver"
 	depends on USB_EHCI_FSL && USB_FSL_USB2 && USB_OTG_FSM && PM
-	select USB_OTG
 	select USB_PHY
 	help
 	  Enable this to support Freescale USB OTG transceiver.
@@ -168,8 +167,7 @@ config USB_QCOM_8X16_PHY
 
 config USB_MV_OTG
 	tristate "Marvell USB OTG support"
-	depends on USB_EHCI_MV && USB_MV_UDC && PM
-	select USB_OTG
+	depends on USB_EHCI_MV && USB_MV_UDC && PM && USB_OTG
 	select USB_PHY
 	help
 	  Say Y here if you want to build Marvell USB OTG transciever