[mips] Range check simm11 and mem_simm11.

Summary:
ldc2/sdc2 now emit slightly worse diagnostics for MIPS-I. The problem
is that they don't trigger the custom parser because all the candidates
are disabled by feature bits. On all other subtargets, the diagnostics are
accurate but are subject to the usual issues of needing to report multiple
ways to correct the code (e.g. smaller offset, enable a CPU feature) but
only being able to report one error.

Reviewers: vkalintiris

Subscribers: dsanders, llvm-commits

Differential Revision: http://reviews.llvm.org/D18436

llvm-svn: 265018