s390/compat: remove superfluous compat wrappers

A couple of compat wrapper functions are simply trampolines to the real
system call. This happened because the compat wrapper defines will only
sign and zero extend system call parameters which are of different size
on s390/s390x (longs and pointers).
All other parameters will be correctly sign and zero extended by the
normal system call wrappers.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>