s390x/tcg: Fix CPU address returned by STIDP

s390x/tcg: Fix CPU address returned by STIDP

In qemu-user-s390x, /proc/cpuinfo contains:

	processor 0: version = 00,  identification = 000000,  machine = 8561
	processor 1: version = 00,  identification = 400000,  machine = 8561

The highest nibble is supposed to contain the CPU address, but it's off
by 2 bits. Fix the shift value and provide a symbolic constant for it.

With the fix we get:

	processor 0: version = 00,  identification = 000000,  machine = 8561
	processor 1: version = 00,  identification = 100000,  machine = 8561

Fixes: 076d4d39b65f ("s390x/cpumodel: wire up cpu type + id for TCG")
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230605113950.1169228-2-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>