arm: Remove unused ffs.S

We've not used ffs.S since we retired armv[45] support. Remove it from
the tree.

Suggested by:		andrew in D37069
Sponsored by:		Netflix

sys/libkern/arm/ffs.S

@@ -1,58 +0,0 @@
-/*	$NetBSD: ffs.S,v 1.3 2003/04/05 23:27:15 bjh21 Exp $	*/
-/*-
- * Copyright (c) 2001 Christopher Gilbert
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. The name of the company nor the name of the author may be used to
- *    endorse or promote products derived from this software without specific
- *    prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- * IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
- * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-	.syntax	unified
-
-/*
- * ffs - find first set bit, this algorithm isolates the first set
- * bit, then multiplies the number by 0x0450fbaf which leaves the top
- * 6 bits as an index into the table.  This algorithm should be a win
- * over the checking each bit in turn as per the C compiled version.
- *
- * under ARMv5 there's an instruction called CLZ (count leading Zero's) that
- * could be used
- *
- * This is the ffs algorithm devised by d.seal and posted to comp.sys.arm on
- * 16 Feb 1994.
- */
-
-ENTRY(ffs)
-
-	/* Standard trick to isolate bottom bit in r0 or 0 if r0 = 0 on entry */
- 	rsb     r1, r0, #0
- 	ands    r0, r0, r1
-	clzne	r0, r0
-	rsbne	r0, r0, #32
-	RET
-END(ffs)
-