ARM: shmobile: fix defconfig warning on CONFIG_USB

A recent update to the marzen_defconfig introduced a
duplicate CONFIG_USB=y line. This removes one of the
two.

arch/arm/configs/marzen_defconfig:86:warning: override: reassigning to symbol USB
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Cc: linux-sh@vger.kernel.org

arch/arm/configs/marzen_defconfig

@@ -83,7 +83,6 @@ CONFIG_USB=y
 CONFIG_USB_RCAR_PHY=y
 CONFIG_MMC=y
 CONFIG_MMC_SDHI=y
-CONFIG_USB=y
 CONFIG_USB_EHCI_HCD=y
 CONFIG_USB_OHCI_HCD=y
 CONFIG_USB_OHCI_HCD_PLATFORM=y