[aarch64][globalisel] Move data into <Target>GenRegisterBankInfo. NFC.

Summary: Depends on D27809

Reviewers: t.p.northover, rovka, qcolombet, ab

Subscribers: aditya_nandakumar, aemerson, rengolin, vkalintiris, dberris, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D27976

llvm-svn: 291897