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

verify/arm64_groundtruth_test.go

@@ -29,6 +29,7 @@ func TestGroundTruthARM64(t *testing.T) {
 		"../testdata/verify/exclusive_arm64.s",
 		"../testdata/verify/shifts_arm64.s",
 		"../testdata/verify/atomics_arm64.s",
+		"../testdata/verify/qmov_arm64.s",
 		"../testdata/verify/crypto_arm64.s",
 		"../testdata/verify/integer_arm64.s",
 		"../testdata/verify/simd_arm64.s",