Convert CONFIG_BOOTARGS to Kconfig

This converts the following to Kconfig:
   CONFIG_BOOTARGS

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/grpeach_defconfig b/configs/grpeach_defconfig
index 417938a..c4a2b44 100644
--- a/configs/grpeach_defconfig
+++ b/configs/grpeach_defconfig
@@ -9,6 +9,8 @@
 CONFIG_RZA1=y
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_BOOTDELAY=3
+CONFIG_USE_BOOTARGS=y
+CONFIG_BOOTARGS="ignore_loglevel"
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_HUSH_PARSER=y
 # CONFIG_CMD_ELF is not set