remove old armv5 code

armv5 dequantizer is not referenced

Change-Id: Id1cc617dcee35ebd6a406816ec6aaa26e8bbc8ad

vp8/decoder/arm/armv5/dequantize_v5.asm

-;
-;  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
-;
-;  Use of this source code is governed by a BSD-style license
-;  that can be found in the LICENSE file in the root of the source
-;  tree. An additional intellectual property rights grant can be found
-;  in the file PATENTS.  All contributing project authors may
-;  be found in the AUTHORS file in the root of the source tree.
-;
-
-
-    EXPORT  |vp8_dequantize_b_armv5|
-
-    AREA    |.text|, CODE, READONLY  ; name this block of code
-
-q       RN  r0
-dqc     RN  r1
-cnt     RN  r2
-
-;void dequantize_b_armv5(short *Q, short *DQC)
-|vp8_dequantize_b_armv5| PROC
-    stmdb   sp!, {r4, lr}
-    ldr     r3, [q]
-    ldr     r4, [dqc], #8
-
-    mov     cnt, #4
-dequant_loop
-    smulbb  lr, r3, r4
-    smultt  r12, r3, r4
-
-    ldr     r3, [q, #4]
-    ldr     r4, [dqc, #-4]
-
-    strh    lr, [q], #2
-    strh    r12, [q], #2
-
-    smulbb  lr, r3, r4
-    smultt  r12, r3, r4
-
-    subs    cnt, cnt, #1
-    ldrne   r3, [q, #4]
-    ldrne   r4, [dqc], #8
-
-    strh    lr, [q], #2
-    strh    r12, [q], #2
-
-    bne     dequant_loop
-
-    ldmia   sp!, {r4, pc}
-    ENDP    ;|vp8_dequantize_b_arm|
-
-    END