MIPS32: Fix codegen register dumps.

Dump raw registers instead of managed registers to be
in line with other architectures. This fixes a checker
failure in 510-checker-try-catch where we have previously
emitted a space that stopped the regexp search. However,
there still remains a runtime failure of the 510 test:
  Exception in thread "main" java.lang.Error:
    Method: "testCatchPhi_double",
    path: ExceptionalFlow1, expected: 3, actual: 0

Change-Id: Ib9ad2c60baf2e322ce1eb58b9dc39feb5ab6f148