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/stmark2_defconfig b/configs/stmark2_defconfig
index c85e3e7..d3507de 100644
--- a/configs/stmark2_defconfig
+++ b/configs/stmark2_defconfig
@@ -9,6 +9,7 @@
 CONFIG_MCFTMR=y
 CONFIG_SYS_LOAD_ADDR=0x40010000
 CONFIG_TIMESTAMP=y
+CONFIG_SYS_MONITOR_BASE=0x47E00400
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0 rw rootfstype=ramfs rdinit=/bin/init devtmpfs.mount=1"
 CONFIG_USE_BOOTCOMMAND=y