readahead: fix number of syscall arguments

readahead: fix number of syscall arguments

The number of readahead arguments depends on architecture and
personality.  For 64bit and ilp32 it equals to 3, for unaligned 32bit it
equals to 4, and for aligned 32bit it equals to 5.

* linux/aarch64/syscallent1.h: Set number of readahead arguments to 3.
* linux/alpha/syscallent.h: Likewise.
* linux/ia64/syscallent.h: Likewise.
* linux/s390x/syscallent.h: Likewise.
* linux/sh64/syscallent.h: Likewise.
* linux/x32/syscallent.h: Likewise.
* linux/x86_64/syscallent.h: Likewise.
* linux/or1k/syscallent.h: Set number of readahead arguments to 4.
* linux/sh/syscallent.h: Likewise.
* linux/tile/syscallent.h: Likewise.
* linux/xtensa/syscallent.h: Set number of readahead arguments to 5.