Revert adding some arch-specific signal syscalls to <linux/syscalls.h>.

It turns out there is some variance on the calling conventions for
these syscalls, and <asm-generic/syscalls.h> is already the mechanism
used to handle this.  Switch arch/tile over to using that mechanism and
tweak the calling conventions for a couple of tile syscalls to match
<asm-generic/syscalls.h>.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/kernel/sys.c

@@ -95,7 +95,7 @@ SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
  */
 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
 		unsigned long, prot, unsigned long, flags,
-		unsigned long, fd, unsigned long, offset)
+		unsigned long, fd, off_t, offset)
 {
 	if (offset & ((1 << PAGE_SHIFT) - 1))
 		return -EINVAL;