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/ls1046ardb_sdcard_defconfig b/configs/ls1046ardb_sdcard_defconfig
index 1afa157..666b892 100644
--- a/configs/ls1046ardb_sdcard_defconfig
+++ b/configs/ls1046ardb_sdcard_defconfig
@@ -10,6 +10,8 @@
 CONFIG_SD_BOOT=y
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_BOOTDELAY=10
+CONFIG_USE_BOOTARGS=y
+CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0 earlycon=uart8250,mmio,0x21c0500 mtdparts=1550000.quadspi:1m(rcw),15m(u-boot),48m(kernel.itb);7e800000.flash:16m(nand_uboot),48m(nand_kernel),448m(nand_free)"
 CONFIG_SPL=y
 CONFIG_SPL_BOARD_INIT=y
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_USE_SECTOR=y