arch/tile: Use <asm-generic/syscalls.h>

With this change we now include <asm-generic/syscalls.h> into the "tile"
version of the header.  To take full advantage of the prototypes there,
we also change our naming convention for "struct pt_regs *" syscalls so
that, e.g., _sys_execve() is the "true" syscall entry, which sets the
appropriate register to point to the pt_regs before calling sys_execve().

While doing this I realized I no longer needed the fork and vfork
entry point stubs, since those functions aren't in the generic
syscall ABI, so I removed them as well.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/kernel/signal.c

@@ -41,8 +41,8 @@
 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 
 
-long _sys_sigaltstack(const stack_t __user *uss,
-		      stack_t __user *uoss, struct pt_regs *regs)
+SYSCALL_DEFINE3(sigaltstack, const stack_t __user *, uss,
+		stack_t __user *, uoss, struct pt_regs *, regs)
 {
 	return do_sigaltstack(uss, uoss, regs->sp);
 }
@@ -78,7 +78,7 @@ int restore_sigcontext(struct pt_regs *regs,
 }
 
 /* sigreturn() returns long since it restores r0 in the interrupted code. */
-long _sys_rt_sigreturn(struct pt_regs *regs)
+SYSCALL_DEFINE1(rt_sigreturn, struct pt_regs *, regs)
 {
 	struct rt_sigframe __user *frame =
 		(struct rt_sigframe __user *)(regs->sp);