S390: Use generic spinlock code.

This patch removes the s390 specific implementation of spinlock code
and is now using the generic one.

ChangeLog:

	* sysdeps/s390/nptl/pthread_spin_init.c: Delete File.
	* sysdeps/s390/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/s390/nptl/pthread_spin_trylock.c: Likewise.
	* sysdeps/s390/nptl/pthread_spin_unlock.c: Likewise.