Use initializer list in the constructor of M68kLegalizerInfo

[0x59616e]

Summary

Using initializer list is cleaner. And also this paves the way for extending the functionality of M68k GISel. NFC.

[0x59616e]

I think the patch of extending functionality on M68kLegalizerInfo won't be too big to review.

So I will merge this patch to the next one.

llvm/lib/Target/M68k/GISel/M68kLegalizerInfo.cpp

   using namespace TargetOpcode;
   const LLT S32 = LLT::scalar(32);
   const LLT P0 = LLT::pointer(0, 32);
-  getActionDefinitionsBuilder(G_LOAD).legalFor({S32});
+  getActionDefinitionsBuilder({G_ADD, G_SUB, G_MUL, G_UDIV, G_LOAD})
+      .legalFor({S32});
   getActionDefinitionsBuilder(G_FRAME_INDEX).legalFor({P0});
-  getActionDefinitionsBuilder(G_ADD).legalFor({S32});
-  getActionDefinitionsBuilder(G_SUB).legalFor({S32});
-  getActionDefinitionsBuilder(G_MUL).legalFor({S32});
-  getActionDefinitionsBuilder(G_UDIV).legalFor({S32});
   getLegacyLegalizerInfo().computeTables();
 }