[AArch64] Improve short-form diags on long-form Match_InvalidOperand.

Since r244955, we try to use the short-form ErrorInfo when both
tries failed, and the long-form match failed on a suffix operand.
However, this means we sometimes mix ErrorInfo and MatchResult
(one manifestation of this being PR24498). Instead, restore both.

llvm-svn: 245469