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/cougarcanyon2_defconfig b/configs/cougarcanyon2_defconfig
index 12f7f74..2a99008 100644
--- a/configs/cougarcanyon2_defconfig
+++ b/configs/cougarcanyon2_defconfig
@@ -3,6 +3,8 @@
 CONFIG_DEFAULT_DEVICE_TREE="cougarcanyon2"
 CONFIG_TARGET_COUGARCANYON2=y
 # CONFIG_ENABLE_MRC_CACHE is not set
+CONFIG_USE_BOOTARGS=y
+CONFIG_BOOTARGS="root=/dev/sdb3 init=/sbin/init rootwait ro"
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
 CONFIG_HUSH_PARSER=y
 # CONFIG_CMD_IMLS is not set