[FastISel][AArch64] Use a new helper function to determine if a value type is supported. NFCI.

FastISel for AArch64 supports more value types than are actually legal. Use a
dedicated helper function to reflect this.

It is very similar to the isLoadStoreTypeLegal function, with the exception
that vector types are not supported yet.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216984 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed