[PowerPC] Clean up -mattr=+vsx tests to always specify -mcpu

We recently discovered an issue that reinforces what a good idea it is
to always specify -mcpu in our code generation tests, particularly for
-mattr=+vsx.  This patch ensures that all tests that specify
-mattr=+vsx also specify -mcpu=pwr7 or -mcpu=pwr8, as appropriate.

Some of the uses of -mattr=+vsx added recently don't make much sense
(when specified for -mtriple=powerpc-apple-darwin8 or -march=ppc32,
for example).  For cases like this I've just removed the extra VSX
test commands; there's enough coverage without them.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220173 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/PowerPC/fp-branch.ll

@@ -1,5 +1,4 @@
 ; RUN: llc < %s -mattr=-vsx -march=ppc32 | grep fcmp | count 1
-; RUN: llc < %s -mattr=+vsx -march=ppc32 | grep xscmpudp | count 1
 
 declare i1 @llvm.isunordered.f64(double, double)