MIPS64: Fix compile error due to -Werror=parentheses

Bug: 
Change-Id: Ifb4d3c8d085ebaf0eaed2c4648871488d94a6997
Reviewed-on: https://chromium-review.googlesource.com/662782Reviewed-by: Miran Karić <Miran.Karic@imgtec.com>
Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Cr-Commit-Position: refs/heads/master@{#47967}

src/mips64/assembler-mips64.cc

@@ -1969,7 +1969,7 @@ void Assembler::sll(Register rd,
   // Don't allow nop instructions in the form sll zero_reg, zero_reg to be
   // generated using the sll instruction. They must be generated using
   // nop(int/NopMarkerTypes).
-  DCHECK(coming_from_nop || rd != zero_reg && rt != zero_reg);
+  DCHECK(coming_from_nop || (rd != zero_reg && rt != zero_reg));
   GenInstrRegister(SPECIAL, zero_reg, rt, rd, sa & 0x1F, SLL);
 }