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/k2g_evm_defconfig b/configs/k2g_evm_defconfig
index e98e953..a9b4afe 100644
--- a/configs/k2g_evm_defconfig
+++ b/configs/k2g_evm_defconfig
@@ -27,6 +27,7 @@
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL_MAX_SIZE=0xfff8
+CONFIG_SPL_BSS_MAX_SIZE=0x8000
 CONFIG_SPL_I2C=y
 CONFIG_SPL_NAND_DRIVERS=y
 CONFIG_SPL_NAND_ECC=y