Correctly handle Tag_CPU_arch_profile.

Fix ARMAttributeParser::CPU_arch_profile so that it doesn't switch on the value
'0' as a legal value of this build attribute.

Change-Id: Ie05a08900a82bb10b78c841b437df747ce3bb38e

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222743 91177308-0d34-0410-b5e6-96231b3b80d8