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/efi-x86_defconfig b/configs/efi-x86_defconfig
index a23d402..bb149c4 100644
--- a/configs/efi-x86_defconfig
+++ b/configs/efi-x86_defconfig
@@ -5,6 +5,8 @@
 CONFIG_DEBUG_UART=y
 CONFIG_FIT=y
 CONFIG_ENV_IS_NOWHERE=y
+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_BOOTM is not set