[GlobalISel] Remove now-unnecessary variable. NFC.
[GlobalISel] Remove now-unnecessary variable. NFC.

Since r296047, we're able to return early on failures.
Don't track whether we succeeded.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@296057 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 0108464498bacd738c7c3f0f45a1faab232808be)

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm