MIPS: generic: Don't explicitly disable CONFIG_USB_SUPPORT

Leave CONFIG_USB_SUPPORT at its default, allowing board config fragments
to make use of USB drivers without needing to override it & trigger
warnings from merge_config.sh.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16948/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/configs/generic_defconfig

@@ -61,7 +61,6 @@ CONFIG_HID_KENSINGTON=y
 CONFIG_HID_LOGITECH=y
 CONFIG_HID_MICROSOFT=y
 CONFIG_HID_MONTEREY=y
-# CONFIG_USB_SUPPORT is not set
 # CONFIG_MIPS_PLATFORM_DEVICES is not set
 # CONFIG_IOMMU_SUPPORT is not set
 CONFIG_EXT4_FS=y