chacha20poly1305: delete unused assembly functions

These are triggering vet errors when vendored into std.

Change-Id: Ied8158941d176129c76509acff7314a6a483c9f9
Reviewed-on: https://go-review.googlesource.com/113176
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

chacha20poly1305/chacha20poly1305_amd64.s

@@ -2693,22 +2693,3 @@ sealAVX2Tail512LoopB:
 	VPERM2I128 $0x13, tmpStoreAVX2, DD3, DD0
 
 	JMP sealAVX2SealHash
-
-// func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
-TEXT ·cpuid(SB), NOSPLIT, $0-24
-	MOVL eaxArg+0(FP), AX
-	MOVL ecxArg+4(FP), CX
-	CPUID
-	MOVL AX, eax+8(FP)
-	MOVL BX, ebx+12(FP)
-	MOVL CX, ecx+16(FP)
-	MOVL DX, edx+20(FP)
-	RET
-
-// func xgetbv() (eax, edx uint32)
-TEXT ·xgetbv(SB),NOSPLIT,$0-8
-	MOVL $0, CX
-	XGETBV
-	MOVL AX, eax+0(FP)
-	MOVL DX, edx+4(FP)
-	RET