[GlobalISel][InlineAsm] Add early return for memory inputs that need to be indirectified

Summary:
D78319 introduced basic support for inline asm input operands in GlobalISel.
However, that patch did not handle the case where a memory input operand still needs to
be indirectified. Later code asserts that the memory operand is already indirect.

This patch adds an early return false to trigger the SelectionDAG fallback for now.

Reviewers: arsenm, paquette

Reviewed By: arsenm

Subscribers: wdng, rovka, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D79955