[mips] Replace call `expandLoadAddress` by `loadAndAddSymbolAddress`. NFC
[mips] Replace call `expandLoadAddress` by `loadAndAddSymbolAddress`. NFC

In case of expanding `lw/sw $reg, symbol($reg)` instruction for PIC it's
enough to call the `loadAndAddSymbolAddress` method. Additional work
performed by the `expandLoadAddress` is not required here.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@369563 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm