cmd/asm: Always use go-style arrangement specifiers on ARM64

Fixing several error message and comment texts of the ARM64 assembler
to use arrangement specifiers of Go's assembly style.

Change-Id: Icdbb14fba7aaede40d57d0d754795b050366a1ab
Reviewed-on: https://go-review.googlesource.com/c/go/+/237859
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
diff --git a/src/cmd/asm/internal/asm/testdata/arm64enc.s b/src/cmd/asm/internal/asm/testdata/arm64enc.s
index 56cf51c..e802ee76 100644
--- a/src/cmd/asm/internal/asm/testdata/arm64enc.s
+++ b/src/cmd/asm/internal/asm/testdata/arm64enc.s
@@ -591,7 +591,7 @@
    FMOVS R8, F15                              // 0f01271e
    FMOVD F2, F9                               // 4940601e
    FMOVS F4, F27                              // 9b40201e
-   //TODO VFMOV $3.125, V8.2D                 // 28f5006f
+   //TODO VFMOV $3.125, V8.D2                 // 28f5006f
    FMSUBS F13, F21, F13, F19                  // b3d50d1f
    FMSUBD F11, F7, F15, F31                   // ff9d4b1f
    //TODO VFMUL V9.S[2], F21, F19             // b39a895f
@@ -648,7 +648,7 @@
    FSUBS F25, F23, F0                         // e03a391e
    FSUBD F11, F13, F24                        // b8396b1e
    //TODO SCVTFSS F30, F20                    // d4db215e
-   //TODO VSCVTF V7.2S, V17.2S                // f1d8210e
+   //TODO VSCVTF V7.S2, V17.S2                // f1d8210e
    SCVTFWS R3, F16                            // 7000221e
    SCVTFWD R20, F4                            // 8402621e
    SCVTFS R16, F12                            // 0c02229e
diff --git a/src/cmd/internal/obj/arm64/asm7.go b/src/cmd/internal/obj/arm64/asm7.go
index 7a5a8ff..bc27740 100644
--- a/src/cmd/internal/obj/arm64/asm7.go
+++ b/src/cmd/internal/obj/arm64/asm7.go
@@ -4801,7 +4801,7 @@
 			Q = 1
 			b = 15
 		} else {
-			c.ctxt.Diag("invalid arrangement, should be 8B or 16B: %v", p)
+			c.ctxt.Diag("invalid arrangement, should be B8 or B16: %v", p)
 			break
 		}