pread, pwrite: fix number of syscall arguments

pread, pwrite: fix number of syscall arguments

The number of pread and pwrite arguments depends on architecture and
personality.  For 64bit and ilp32 it equals to 4, for unaligned
32bit it equals to 5, and for aligned 32bit it equals to 6.

* linux/aarch64/syscallent1.h: Change the number of pread and pwrite
arguments to 4.
* linux/alpha/syscallent.h: Likewise.
* linux/mips/syscallent-n32.h: Likewise.
* linux/mips/syscallent-n64.h: Likewise.
* linux/s390x/syscallent.h: Likewise.
* linux/sh64/syscallent.h: Likewise.
* linux/tile/syscallent.h: Likewise.
* linux/x32/syscallent.h: Likewise.
* linux/x86_64/syscallent.h: Likewise.
* linux/or1k/syscallent.h: Change the number of pread and pwrite
arguments to 5.