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/ls1021atwr_qspi_defconfig b/configs/ls1021atwr_qspi_defconfig
index 06ef255..3f70ca7 100644
--- a/configs/ls1021atwr_qspi_defconfig
+++ b/configs/ls1021atwr_qspi_defconfig
@@ -10,6 +10,8 @@
 CONFIG_QSPI_BOOT=y
 CONFIG_ENV_IS_IN_SPI_FLASH=y
 CONFIG_BOOTDELAY=3
+CONFIG_USE_BOOTARGS=y
+CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0"
 CONFIG_SILENT_CONSOLE=y
 # CONFIG_CONSOLE_MUX is not set
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y