common: Move CONFIG_BOOTARGS to Kconfig

Also introduce CONFIG_USE_BOOTARGS option so we can control if
CONFIG_BOOTARGS defined at all.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
[trini: Resync r8a779[56]_ulcb, various ls10xx targets]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/novena_defconfig b/configs/novena_defconfig
index a75e27d..9af6018 100644
--- a/configs/novena_defconfig
+++ b/configs/novena_defconfig
@@ -16,6 +16,8 @@
 CONFIG_FIT=y
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/mach-imx/spl_sd.cfg,MX6Q"
 CONFIG_ENV_IS_IN_MMC=y
+CONFIG_USE_BOOTARGS=y
+CONFIG_BOOTARGS="console=ttymxc1,115200 "
 CONFIG_VERSION_VARIABLE=y
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL=y