[mips] Set the hasNoSchedulingInfo flag for the `MipsAsmPseudoInst`

Set the hasNoSchedulingInfo flag for the`MipsAsmPseudoInst`. These
pseudo-instructions are never used by codegen. This flag allows to
reduce number of "No schedule information for" and "lacks information
for" errors in case of marking a scheduler model as complete.

This patch is one of a series of patches. The goal is to make P5600
scheduler model complete and turn on the `CompleteModel` flag.

Differential Revision: https://reviews.llvm.org/D63236

llvm-svn: 363701