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/sama5d2_xplained_emmc_defconfig b/configs/sama5d2_xplained_emmc_defconfig
index 12ad0a4..32d87ec 100644
--- a/configs/sama5d2_xplained_emmc_defconfig
+++ b/configs/sama5d2_xplained_emmc_defconfig
@@ -32,6 +32,7 @@
 CONFIG_BOOTCOMMAND="fatload mmc 0:1 0x22000000 at91-sama5d2_xplained.dtb; fatload mmc 0:1 0x23000000 zImage; bootz 0x23000000 - 0x22000000"
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_SPL_MAX_SIZE=0x10000
+CONFIG_SPL_BSS_MAX_SIZE=0x80000
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_CBSIZE=256
 CONFIG_SYS_PBSIZE=276