[RegisterConfiguration] Streamline access to arch defaults, simplify Registers.

src/mips/macro-assembler-mips.cc

Index: src/mips/macro-assembler-mips.cc
diff --git a/src/mips/macro-assembler-mips.cc b/src/mips/macro-assembler-mips.cc
index a07ebd5b434ccb5e2809fe3dce7e6d0e48b086da..1c877cb8d4fac48a5872bfffa534de10fbc669dd 100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -6719,8 +6719,7 @@ Register GetRegisterThatIsNotOneOf(Register reg1,
   if (reg5.is_valid()) regs |= reg5.bit();
   if (reg6.is_valid()) regs |= reg6.bit();
 
-  const RegisterConfiguration* config =
-      RegisterConfiguration::ArchDefault(RegisterConfiguration::CRANKSHAFT);
+  const RegisterConfiguration* config = RegisterConfiguration::Crankshaft();
   for (int i = 0; i < config->num_allocatable_general_registers(); ++i) {
     int code = config->GetAllocatableGeneralCode(i);
     Register candidate = Register::from_code(code);