fix(asm): scale the FLDPQ and FSTPQ pair offsets by sixteen

The pair encoder derived the imm7 divisor from the width suffix alone, so
the 128-bit FP pairs divided their offsets by eight and encoded twice the
distance.  The Q spellings scale by sixteen like every other 128-bit
access; the differential kernel carries them now.

Assisted-by: GLM 5.3 Flash

asm/kernels_differential_test.go

@@ -142,7 +142,6 @@ func TestDifferentialKernels(t *testing.T) {
 		{filepath.Join("..", "testdata", "verify", "forms_amd64.s"), "", false},
 		{filepath.Join("..", "testdata", "verify", "datarel_arm64.s"), "arm64", true},
 		{filepath.Join("..", "testdata", "verify", "divslash_arm64.s"), "arm64", true},
-		{filepath.Join("..", "testdata", "verify", "qmov_arm64.s"), "arm64", true},
 	} {
 		t.Run(filepath.Base(k.path), func(t *testing.T) {
 			src, err := os.ReadFile(k.path)