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/sama5d4_xplained_nandflash_defconfig b/configs/sama5d4_xplained_nandflash_defconfig
index b2079f0..f5313d7 100644
--- a/configs/sama5d4_xplained_nandflash_defconfig
+++ b/configs/sama5d4_xplained_nandflash_defconfig
@@ -14,6 +14,8 @@
 CONFIG_SYS_EXTRA_OPTIONS="SAMA5D4,SYS_USE_NANDFLASH"
 CONFIG_ENV_IS_IN_NAND=y
 CONFIG_BOOTDELAY=3
+CONFIG_USE_BOOTARGS=y
+CONFIG_BOOTARGS="console=ttyS0,115200 earlyprintk mtdparts=atmel_nand:256k(bootstrap)ro,512k(uboot)ro,256K(env),256k(env_redundant),256k(spare),512k(dtb),6M(kernel)ro,-(rootfs) rootfstype=ubifs ubi.mtd=7 root=ubi0:rootfs"
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_SPL=y
 CONFIG_HUSH_PARSER=y