sh: Remove stale microdev board

sh: Remove stale microdev board

This board was an early prototype platform for early SH4 CPUs and related
to the already removed SH5 cayman platform.

The microdev board itself has been kept in the tree for this long despite
being in a bad shape even 20 years ago when it got merged, with no working
PCI support and ugly workarounds for its I/O port implementation that
try to emulate PC style peripheral access despite being quite different
in reality.

As far as I can tell, the ethernet, display, USB and PCI devices on it
already broke at some point (afbb9d8d5266b, 46bc85872040a), so I think
we can just removeit entirely.

Link: https://lore.kernel.org/lkml/09094baf-dadf-4bce-9f63-f2a1f255f9a8@app.fastmail.com/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/20230914155523.3839811-1-arnd@kernel.org
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>