Using a register variable for r4 is not necessary.  Let the
compiler decide the register to be used.
Reported-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>