preadv, pwritev: fix number of syscall arguments

preadv, pwritev: fix number of syscall arguments

The number of preadv and pwritev 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 preadv and pwritev
arguments to 4.
* linux/alpha/syscallent.h: Likewise.
* linux/ia64/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/powerpc/syscallent.h: Change the number of preadv and pwritev
arguments to 6.
* linux/sh/syscallent.h: Likewise.
* linux/xtensa/syscallent.h: Likewise.