chromeos: provide option to dynamically allocate ram oops buffer

Fixing the location of the ram oops buffer can lead to certain
kernel and boot loaders being confused when there is a ram
reservation low in the address space. Alternatively provide
a mechanism to allocate the ram oops buffer in cbmem. As cbmem
is usually high in the address space it avoids low reservation
confusion.

The patch uncondtionally provides a GOOG9999 ACPI device with
a single memory resource describing the memory region used for
the ramoops region.

BUG=None
BRANCH=baytrail,haswell
TEST=Built and booted with and w/o dynamic ram oops. With
     the corresponding kernel change things behave correctly.

Change-Id: Ide2bb4434768c9f9b90e125adae4324cb1d2d073
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/5257
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/vendorcode/google/chromeos/gnvs.c

@@ -72,6 +72,8 @@ void chromeos_init_vboot(chromeos_acpi_t *chromeos)
 			    reason ? reason : ELOG_CROS_RECOVERY_MODE_BUTTON);
 	}
 #endif
+
+	chromeos_ram_oops_init(chromeos);
 }
 
 void chromeos_set_me_hash(u32 *hash, int len)