[TypeCHecker] Tests/NFC: Restrict SIMD performance test to macOS only

The test is flaky in some simulator and x86_64 configurations, let's
try to restrict it even further to minimize CI impact.

Resolves: rdar://157636003

Author: xedin

validation-test/Sema/type_checker_perf/fast/simd_scalar_multiple.swift.gyb

@@ -2,8 +2,9 @@
 
 // REQUIRES: asserts,no_asan
 
-// Flaky is some simulator configurations
+// Flaky is some configurations including simulators
 // REQUIRES: OS=macosx
+// REQUIRES: CPU=arm64 || CPU=arm64e
 
 func f(c: Float, a: SIMD2<Float>) -> SIMD2<Float> {
   return (c * a)