Previous PR #1758 implements the generic getValidAddr to get pure
vaddr without any tags or sign-extend bits.
In RISC-V implementation, the getValidAddr will zero-extend
address in RV32 mode and use it to do TLB translation. Use
getValidAddr to get zero-extend vaddr can reduce zero-extend
repetition
Change-Id: I2273ce48bccb873790103ba0fcdb0b48de9ced4c
40ccb8b171