s390/ptrace: move short psw definitions to ptrace header file

The short psw definitions are contained in compat header files, however
short psws are not compat specific. Therefore move the definitions to
ptrace header file. This also gets rid of a compat header include in kvm
code.

Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>