Apply merging to s_load as is done for s_buffer_load. Reviewed By: foad Differential Revision: https://reviews.llvm.org/D130742
This change includes tablegen patterns that were missed by https://reviews.llvm.org/D110950 and https://reviews.llvm.org/D76230 Reviewed By: foad Differential Revision: https://reviews.llvm.org/D119302