[PowerPC] Remove SPE from triple in VSX test

This test does not fail because the PPCSubtarget was not initialized,
and otherwise a fatal error occurs:
"SPE and traditional floating point cannot both be enabled.".

Tested by adding `-mllvm -enable-matrix` to the existing command-line.

Author: guy-david

clang/test/CodeGen/PowerPC/builtins-ppc-fpconstrained.c

@@ -11,7 +11,7 @@
 // RUN: -S -ffp-exception-behavior=strict \
 // RUN: -o - %s | FileCheck --check-prefix=CHECK-ASM \
 // RUN: --check-prefix=FIXME-CHECK  %s
-// RUN: %clang_cc1 -triple powerpcspe -ffp-exception-behavior=strict \
+// RUN: %clang_cc1 -triple powerpc -ffp-exception-behavior=strict \
 // RUN: -target-feature +vsx -fexperimental-strict-floating-point -emit-llvm \
 // RUN: %s -o - | FileCheck --check-prefix=CHECK-CONSTRAINED %s