commonlib/region: Turn addrspace_32bit into a more official API

We had the addrspace_32bit rdev in prog_loaders.c for a while to help
represent memory ranges as an rdev, and we've found it useful for a
couple of things that have nothing to do with program loading. This
patch moves the concept straight into commonlib/region.c so it is no
longer anchored in such a weird place, and easier to use in unit tests.
Also expand the concept to the whole address space (there's no real need
to restrict it to 32 bits in 64-bit environments) and introduce an
rdev_chain_mem() helper function to make it a bit easier to use. Replace
some direct uses of struct mem_region_device with this new API where it
seems to make sense.

Signed-off-by: Julius Werner <jwerner@chromium.org>
Change-Id: Ie4c763b77f77d227768556a9528681d771a08dca
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52533
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
diff --git a/src/lib/cbfs.c b/src/lib/cbfs.c
index 23e8f41..32ebfaf 100644
--- a/src/lib/cbfs.c
+++ b/src/lib/cbfs.c
@@ -89,7 +89,7 @@
 		return -1;
 
 	size_t msize = be32toh(fh->mdata.h.offset);
-	if (rdev_chain(&fh->metadata, &addrspace_32bit.rdev, (uintptr_t)&fh->mdata, msize))
+	if (rdev_chain_mem(&fh->metadata, &fh->mdata, msize))
 		return -1;
 
 	if (type) {
@@ -436,7 +436,7 @@
 		void *compr_start = prog_start(pstage) + prog_size(pstage) - in_size;
 		if (rdev_readat(&rdev, compr_start, 0, in_size) != in_size)
 			return CB_ERR;
-		rdev_chain(&rdev, &addrspace_32bit.rdev, (uintptr_t)compr_start, in_size);
+		rdev_chain_mem(&rdev, compr_start, in_size);
 	}
 
 	size_t fsize = cbfs_load_and_decompress(&rdev, prog_start(pstage), prog_size(pstage),