ARM: OMAP2+: Fix Kconfig dependencies for USB_ARCH_HAS_EHCI

Otherwise we get:

warning: (ARCH_OMAP3 && ARCH_OMAP4) selects USB_ARCH_HAS_EHCI
which has unmet direct dependencies (USB_SUPPORT)
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/Kconfig

@@ -32,7 +32,7 @@ config ARCH_OMAP3
 	depends on ARCH_OMAP2PLUS
 	default y
 	select CPU_V7
-	select USB_ARCH_HAS_EHCI
+	select USB_ARCH_HAS_EHCI if USB_SUPPORT
 	select ARCH_HAS_OPP
 	select PM_OPP if PM
 	select ARM_CPU_SUSPEND if PM
@@ -52,7 +52,7 @@ config ARCH_OMAP4
 	select ARM_ERRATA_720789
 	select ARCH_HAS_OPP
 	select PM_OPP if PM
-	select USB_ARCH_HAS_EHCI
+	select USB_ARCH_HAS_EHCI if USB_SUPPORT
 	select ARM_CPU_SUSPEND if PM
 
 comment "OMAP Core Type"