s390/alternatives: use insn format for new instructions

Use insn format with instruction format specifier instead of plain
longs. This way it is also more obvious that code instead of data is
generated.

The generated code is identical.

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