unix: fix typo in unix/asm_linux_arm64.s made in 28a7276

28a7276 causes following error with GOARCH=arm64 environment.

  # golang.org/x/sys/unix
  asm: InitTextSym double init for "".Syscall
  asm: symbol "".Syscall listed multiple times
  asm: invalid encoding for argument 00004 (/home/junya/go/src/golang.org/x/sys/unix/asm_linux_arm64.s:21)        CALL    runtime.entersyscall(SB)
  asm: invalid encoding for argument 00048 (/home/junya/go/src/golang.org/x/sys/unix/asm_linux_arm64.s:32)        CALL    runtime.exitsyscall(SB)
  asm: makeFuncDebugEntry double process "".Syscall
  asm: assembly failed

Change-Id: Ic7895fecc5f4b1fd6ebef63603c5f720227f5130
Reviewed-on: https://go-review.googlesource.com/86135
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

unix/asm_linux_arm64.s

@@ -17,7 +17,7 @@ TEXT ·Syscall(SB),NOSPLIT,$0-56
 TEXT ·Syscall6(SB),NOSPLIT,$0-80
 	B	syscall·Syscall6(SB)
 
-TEXT ·Syscall(SB),NOSPLIT,$0-48
+TEXT ·SyscallNoError(SB),NOSPLIT,$0-48
 	BL	runtime·entersyscall(SB)
 	MOVD	a1+8(FP), R0
 	MOVD	a2+16(FP), R1