alpha: switch to generic sys_execve()

get rid of sys_execve() wrapper, while we are at it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/alpha/kernel/entry.S

@@ -744,15 +744,6 @@ sys_rt_sigreturn:
 	br	ret_from_sys_call
 .end sys_rt_sigreturn
 
-	.align	4
-	.globl	sys_execve
-	.ent	sys_execve
-sys_execve:
-	.prologue 0
-	mov	$sp, $19
-	jmp	$31, do_sys_execve
-.end sys_execve
-
 	.align	4
 	.globl	alpha_ni_syscall
 	.ent	alpha_ni_syscall