linux: Add missing config options to generic configs

These missing options have been noticed while enabling the following
configuration options on ipq806x, but they're available in the standard
kernel:
*ARCH_QCOM
*CONFIG_USB_SUPPORT
*CONFIG_USB_DWC3
*CONFIG_MFD_SYSCON

Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45256 3c298f89-4303-0410-b956-a3cf2f4a3e73