[clang] Remove redundant --check-prefix=CHECK from tests

[hans]

Looks good to me.

test/CodeGen/ms-mm-align.c

 // RUN: %clang_cc1 -ffreestanding -fms-extensions -fms-compatibility -fms-compatibility-version=17.00 -target-feature +sse \
 // RUN:         -triple i686--windows -emit-llvm %s -o - \
-// RUN:         | FileCheck %s -check-prefix CHECK
+// RUN:         | FileCheck %s
 
 // intrin.h needs size_t, but -ffreestanding prevents us from getting it from
 // stddef.h.  Work around it with this typedef.
 typedef __SIZE_TYPE__ size_t;
 #include <intrin.h>
 
 void capture_ptr(int* i);
 void test_mm_align16(int p) {
   _MM_ALIGN16 int i;
   capture_ptr(&i);
 }
 
 // CHECK: alloca i32, align 16

test/CodeGen/windows-on-arm-stack-probe-size.c

 // RUN: %clang_cc1 -triple thumbv7-windows-itanium -mstack-probe-size=8096 -fms-extensions -O2 -emit-llvm %s -o - \
 // RUN:     | FileCheck %s -check-prefix CHECK-8096
 
 // RUN: %clang_cc1 -triple thumbv7-windows-itanium -mstack-probe-size=4096 -fms-extensions -O2 -emit-llvm %s -o - \
 // RUN:     | FileCheck %s -check-prefix CHECK-4096
 
 // RUN: %clang_cc1 -triple thumbv7-windows-itanium -fms-extensions -O2 -emit-llvm %s -o - \
-// RUN:     | FileCheck %s -check-prefix CHECK
+// RUN:     | FileCheck %s
 
 __declspec(dllimport) void initialise(signed char buffer[4096]);
 
 __declspec(dllexport) signed char function(unsigned index) {
   signed char buffer[4096];
   initialise(buffer);
   return buffer[index];
 }