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/pm9263_defconfig b/configs/pm9263_defconfig
index 7516c95..d25b7a8 100644
--- a/configs/pm9263_defconfig
+++ b/configs/pm9263_defconfig
@@ -6,6 +6,8 @@
 CONFIG_SYS_EXTRA_OPTIONS="AT91SAM9263"
 CONFIG_ENV_IS_IN_FLASH=y
 CONFIG_BOOTDELAY=3
+CONFIG_USE_BOOTARGS=y
+CONFIG_BOOTARGS="root=/dev/mtdblock4 rootfstype=jffs2 fbcon=rotate:3 "
 # CONFIG_CONSOLE_MUX is not set
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_BOARD_EARLY_INIT_F=y