s390/kvm,gaccess: shorten put/get_guest code

The put_guest_u*/get_guest_u* are nothing but wrappers for the regular
put_user/get_user uaccess functions. The only difference is that before
accessing user space the guest address must be translated to a user space
address.
Change the order of arguments for the guest access functions so they
match their uaccess parts. Also remove the u* suffix, so we simply
have put_guest/get_guest which will automatically use the right size
dependent on pointer type of the destination/source that now must be
correct.
In result the same behaviour as put_user/get_user except that accesses
must be aligned.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>