s390/alternatives: Remove noaltinstr option

The current Kernel doesn't boot without alternative patching on
z16 machines. To avoid such bugs in the future, remove the option
disable alternative patching.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>