Convert CONFIG_SYS_MONITOR_BASE to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_MONITOR_BASE

Note that for how this is re-used on some PowePC platforms, we introduce
CONFIG_SPL_SYS_MONITOR_BASE and CONFIG_TPL_SYS_MONITOR_BASE and use the
CONFIG_VAL macro to get the correct value at build time, in the code.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/chromebook_coral_defconfig b/configs/chromebook_coral_defconfig
index 70d62c0..4e438ca 100644
--- a/configs/chromebook_coral_defconfig
+++ b/configs/chromebook_coral_defconfig
@@ -22,6 +22,7 @@
 CONFIG_X86_OFFSET_SPL=0xffe80000
 CONFIG_INTEL_ACPIGEN=y
 CONFIG_INTEL_GENERIC_WIFI=y
+CONFIG_SYS_MONITOR_BASE=0x01110000
 CONFIG_CHROMEOS=y
 CONFIG_BOOTSTAGE=y
 CONFIG_SPL_BOOTSTAGE=y