[AVR] Remove unnecessary casts (NFC) (#155791)

getSubtargetImpl() already returns const AVRSubtarget *.

llvm/lib/Target/AVR/AVRAsmPrinter.cpp

diff --git a/llvm/lib/Target/AVR/AVRAsmPrinter.cpp b/llvm/lib/Target/AVR/AVRAsmPrinter.cpp
index 0fb33cd..ad8f7d8 100644
--- a/llvm/lib/Target/AVR/AVRAsmPrinter.cpp
+++ b/llvm/lib/Target/AVR/AVRAsmPrinter.cpp
@@ -245,7 +245,7 @@
 bool AVRAsmPrinter::doFinalization(Module &M) {
   const TargetLoweringObjectFile &TLOF = getObjFileLowering();
   const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
-  const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl();
+  const AVRSubtarget *SubTM = TM.getSubtargetImpl();
 
   bool NeedsCopyData = false;
   bool NeedsClearBSS = false;
@@ -294,7 +294,7 @@
 
 void AVRAsmPrinter::emitStartOfAsmFile(Module &M) {
   const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();
-  const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl();
+  const AVRSubtarget *SubTM = TM.getSubtargetImpl();
   if (!SubTM)
     return;