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/qemu-x86_64_defconfig b/configs/qemu-x86_64_defconfig
index 36214fc..cc8393e 100644
--- a/configs/qemu-x86_64_defconfig
+++ b/configs/qemu-x86_64_defconfig
@@ -20,6 +20,7 @@
 CONFIG_FIT=y
 CONFIG_SPL_LOAD_FIT=y
 # CONFIG_USE_SPL_FIT_GENERATOR is not set
+CONFIG_SYS_MONITOR_BASE=0x01110000
 CONFIG_BOOTSTAGE=y
 CONFIG_BOOTSTAGE_REPORT=y
 CONFIG_SHOW_BOOT_PROGRESS=y