[RISCV][NFC] Fix naming of RISCVISelLowering::{LowerRETURNADDR,LowerFRAMEADDR}

Rename to lowerRETURNADDR, lowerFRAMEADDR in order to be consistent with the 
LLVM coding style and the other functions in this file.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343752 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed