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/P1020RDB-PC_SDCARD_defconfig b/configs/P1020RDB-PC_SDCARD_defconfig
index f2ac78c..174729a 100644
--- a/configs/P1020RDB-PC_SDCARD_defconfig
+++ b/configs/P1020RDB-PC_SDCARD_defconfig
@@ -18,6 +18,7 @@
 CONFIG_FIT_VERBOSE=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
+CONFIG_SPL_SYS_MONITOR_BASE=0xF8F81000
 CONFIG_BOOTDELAY=10
 CONFIG_USE_BOOTCOMMAND=y
 CONFIG_BOOTCOMMAND="setenv bootargs root=/dev/$bdev rw rootdelay=30 console=$consoledev,$baudrate $othbootargs;usb start;ext2load usb 0:1 $loadaddr /boot/$bootfile;ext2load usb 0:1 $fdtaddr /boot/$fdtfile;bootm $loadaddr - $fdtaddr"