[clang-format] fix regression in middle pointer alignment

Summary:
a75f8d98 introduced a regression with Middle pointer alignment,
which this patch fixes.

Reviewers: MyDeveloperDay, klimek, sammccall

Reviewed By: MyDeveloperDay, sammccall

Subscribers: cfe-commits, merge_guards_bot

Patch by: Typz

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70305