parisc: Add runtime check to prevent PA2.0 kernels on PA1.x machines

[ Upstream commit 591d2108f3abc4db9f9073cae37cf3591fd250d6 ]

If a 32-bit kernel was compiled for PA2.0 CPUs, it won't be able to run
on machines with PA1.x CPUs. Add a check and bail out early if a PA1.x
machine is detected.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>