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/ls2080a_simu_defconfig b/configs/ls2080a_simu_defconfig
index 1a4f80c..30afa32 100644
--- a/configs/ls2080a_simu_defconfig
+++ b/configs/ls2080a_simu_defconfig
@@ -8,6 +8,8 @@
 CONFIG_SYS_EXTRA_OPTIONS="SIMU"
 CONFIG_ENV_IS_NOWHERE=y
 CONFIG_BOOTDELAY=10
+CONFIG_USE_BOOTARGS=y
+CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0 earlycon=uart8250,mmio,0x21c0500 ramdisk_size=0x2000000 default_hugepagesz=2m hugepagesz=2m hugepages=256"
 # CONFIG_DISPLAY_BOARDINFO is not set
 # CONFIG_CMD_CONSOLE is not set
 # CONFIG_CMD_IMLS is not set