Remove the bogus selects on USB-related symbols for 6345 and 6338, not
only we do not yet support USB on BCM63XX, but they also cause the
following warnings:

warning: (BCM63XX_CPU_6338 && BCM63XX_CPU_6345) selects
USB_OHCI_BIG_ENDIAN_MMIO which has unmet direct dependencies
(USB_SUPPORT && USB && USB_OHCI_HCD)
warning: (BCM63XX_CPU_6338 && BCM63XX_CPU_6345) selects
USB_OHCI_BIG_ENDIAN_DESC which has unmet direct dependencies
(USB_SUPPORT && USB && USB_OHCI_HCD)
make[4]: Leaving directory `/home/florian/dev/linux'

Just get rid of these bogus Kconfig selects because neither 6345 nor
6338 actually have built-in USB host controllers.
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: cernekee@gmail.com
Cc: jogo@openwrt.org
Patchwork: http://patchwork.linux-mips.org/patch/5497/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>