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/evb-rk3568_defconfig b/configs/evb-rk3568_defconfig
index a45fac0..867868b 100644
--- a/configs/evb-rk3568_defconfig
+++ b/configs/evb-rk3568_defconfig
@@ -26,6 +26,7 @@
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_SPL_MAX_SIZE=0x20000
 CONFIG_SPL_PAD_TO=0x7f8000
+CONFIG_SPL_BSS_MAX_SIZE=0x4000
 # CONFIG_SPL_RAW_IMAGE_SUPPORT is not set
 CONFIG_SPL_STACK_R=y
 CONFIG_SPL_ATF=y