Makefiles: Remove -D__PRE_RAM__

All cases of testing for __PRE_RAM__ have been converted
to equivalent ENV_xxx definitions from <rules.h>.

Change-Id: Ib6cd598f17109cc1072818cebe4791f7410c3428
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37075
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

toolchain.inc

@@ -70,7 +70,7 @@ CFLAGS_ppc64	+=
 # stack use, we use 1.5K as heuristic, assuming that we typically have lots
 # of tiny stack frames and the odd large one.
 #
-# Store larger buffers in BSS, use MAYBE_STATIC_BSS to share code with __PRE_RAM__
+# Store larger buffers in BSS, use MAYBE_STATIC_BSS to share data in cache-as-ram
 # on x86.
 # Since GCCs detection of dynamic array bounds unfortunately seems to be
 # very basic, you'll sometimes have to use a static upper bound for the