Move socket and ipc subcall entries to subcall.h

Move socket and ipc subcall entries to subcall.h

Syscall entries for socket and ipc subcalls are the same on all
architectures, or at least they should be the same, so move them
to the single file.

* linux/subcall.h: Add syscall entries for socket and ipc subcalls.
* linux/arm/syscallent.h: Remove entries for socket and ipc subcalls.
* linux/i386/syscallent.h: Likewise.
* linux/m68k/syscallent.h: Likewise.
* linux/powerpc/syscallent.h: Likewise.
* linux/s390/syscallent.h: Likewise.
* linux/s390x/syscallent.h: Likewise.
* linux/sh/syscallent.h: Likewise.
* linux/sh64/syscallent.h: Likewise.
* linux/sparc/syscallent.h: Likewise.