[RegisterBankInfo] Make addRegBankCoverage more capable to ease
targeting jobs.
Now, addRegBankCoverage also adds the subreg-classes not just the
sub-classes of the given register class.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265469 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed