We can use the existing SVD patching framework to build SVD files which define the peripherals common to all Cortex-M devices.
The base SVD files are armv6m.svd, armv7m.svd, and armv7em.svd, which do
not contain any peripherals. They are patched to create armv6m.svd.patched
and armv7m.patched using svd patch and the armv6m.yaml and
armv7m.yaml device files. The peripheral definitions all come from
the peripherals/ directory.