arm: Use unified syntax, ldrsheq instead of ldreqsh

clang only supports the new, unified arm syntax (UAL), while binutils
gas supports both (and defaults to the old syntax). Explicitly declare
that the unified syntax is used, and use the right form of these
instructions that is supported by both.

Change-Id: I9a3940e060c129861c7a542ccf09035dbd1766ae
2 files changed