[AArch64] CCSIDR2 system register

Implement the 'Current Cache Size' register that has been introduced
as part of the Armv8.3 architecture. I originally missed this, and
(hopefully) should be the final patch for assembler support.

Differential Revision: https://reviews.llvm.org/D41396


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321155 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed