[WebAssembly] Refactor tablegen for store instructions (NFC)

Summary: Add patterns similar to loads.

Differential Revision: https://reviews.llvm.org/D45064

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@328876 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed