add buildroot and linux kernel extra configs

Signed-off-by: Rabeeh Khoury <rabeeh@solid-run.com>

configs/buildroot/lx2160acex7_defconfig

+BR2_aarch64=y
+BR2_cortex_a72=y
+BR2_TOOLCHAIN_BUILDROOT_GLIBC=y
+BR2_TOOLCHAIN_BUILDROOT_CXX=y
+BR2_PACKAGE_BUSYBOX_SHOW_OTHERS=y
+BR2_PACKAGE_I2C_TOOLS=y
+BR2_PACKAGE_RNG_TOOLS=y
+BR2_PACKAGE_BASH=y
+BR2_PACKAGE_TAR=y
+BR2_PACKAGE_UTIL_LINUX=y
+BR2_PACKAGE_UTIL_LINUX_HWCLOCK=y

configs/linux/lx2k_additions.config

+CONFIG_USB_SERIAL=y
+CONFIG_USB_SERIAL_CONSOLE=y
+CONFIG_USB_SERIAL_GENERIC=y
+CONFIG_USB_SERIAL_SIMPLE=y
+CONFIG_USB_SERIAL_FTDI_SIO=y
+CONFIG_BLK_DEV_NVME=y
+CONFIG_NVMEM_BCM_OCOTP=y
+