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/trats2_defconfig b/configs/trats2_defconfig
index f91ec1d..df0f4b1 100644
--- a/configs/trats2_defconfig
+++ b/configs/trats2_defconfig
@@ -6,6 +6,8 @@
 # CONFIG_SYS_MALLOC_CLEAR_ON_INIT is not set
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y
+CONFIG_USE_BOOTARGS=y
+CONFIG_BOOTARGS="Please use defined boot"
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
 CONFIG_HUSH_PARSER=y