Convert CONFIG_SPL_BSS_MAX_SIZE et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SPL_BSS_MAX_SIZE
   CONFIG_SPL_MAX_FOOTPRINT

Note that the da850evm platforms were violating the "only use one" rule
here, and so now hard-code their BSS limit.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/smdk5420_defconfig b/configs/smdk5420_defconfig
index 1658eea..cad63be 100644
--- a/configs/smdk5420_defconfig
+++ b/configs/smdk5420_defconfig
@@ -23,6 +23,8 @@
 CONFIG_SILENT_CONSOLE=y
 CONFIG_CONSOLE_MUX=y
 # CONFIG_SPL_FRAMEWORK is not set
+CONFIG_SPL_FOOTPRINT_LIMIT=y
+CONFIG_SPL_MAX_FOOTPRINT=0x7800
 CONFIG_SYS_PROMPT="SMDK5420 # "
 CONFIG_SYS_PBSIZE=1024
 CONFIG_CMD_GPIO=y