lib: Rewrite qemu-armv7 ramdetect

* Move armv7 RAM dection to a common place
* Enable it for all emulated platforms
* Use 32bit probe values and restore memory even on failure
* Use the new logic on the following boards:
** qemu-armv7
** qemu-riscv

Tested on qemu-system-riscv:
Fixes kernel panic due to wrong memory limits reported.

Change-Id: I37386c6a95bfc3b7b25aeae32c6e14cff9913513
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33934
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/include/ramdetect.h

@@ -0,0 +1,22 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+/*
+ * Probe an area if it's read/writable.
+ * Primary use case is the detection of DRAM amount on emulators.
+ *
+ * @param dram_start Physical address of DRAM start
+ * @param probe_size Maximum size in MiB to probe for
+ * @return The detected DRAM size in MiB
+ */
+size_t probe_ramsize(const uintptr_t dram_start, const size_t probe_size);