[CSInfo][MIPS] Describe parameter value loaded by ADDiu

Describe parameter's value loaded by MIPS ADDiu instruction.
When parameter's value is loaded into a register by mips ADDiu/DADDiu
instruction, it could be described correctly and emitted as
DW_AT_GNU_call_site_value.

Patch by Nikola Tesic

Differential revision: https://reviews.llvm.org/D78108