Revert "Kconfig: Bring HEAP_SIZE to a common, large value"

This reverts commit 44a48ce7a4.

Reason for revert: It breaks wakeup from suspend on a bunch of boards.

While this approach of eyeballing "correct" values by chipset _should_
be fixed, it should also be accompanied by compile time verification
that the memory map works out.

Since nobody seems to care enough, let's just revert this, instead of
keeping the tree broken for a bunch of configurations.

Change-Id: I3cd73b6ce8b15f06d3480a03ab472dcd444d7ccc
Signed-off-by: Patrick Georgi <patrick@coreboot.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78850
Reviewed-by: Matt DeVillier <matt.devillier@amd.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@gmail.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Subrata Banik <subratabanik@google.com>

src/cpu/qemu-x86/Kconfig

@@ -35,4 +35,7 @@ config MAX_CPUS
 	default 32 if SMM_TSEG
 	default 4
 
+config HEAP_SIZE
+	default 0x8000
+
 endif