[mips] Use `formatImm` call to print immediate value in the `MipsInstPrinter`

That allows, for example, to print hex-formatted immediates using
llvm-objdump --print-imm-hex command line option.

Differential Revision: http://reviews.llvm.org/D18195

llvm-svn: 263704
diff --git a/llvm/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp b/llvm/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
index f2ef0b2..768ed20 100644
--- a/llvm/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
+++ b/llvm/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
@@ -195,7 +195,7 @@
   }
 
   if (Op.isImm()) {
-    O << Op.getImm();
+    O << formatImm(Op.getImm());
     return;
   }
 
@@ -211,7 +211,7 @@
     Imm -= Offset;
     Imm &= (1 << Bits) - 1;
     Imm += Offset;
-    O << Imm;
+    O << formatImm(Imm);
     return;
   }