[lldb] Remove redundant nullptr check (NFC) (#182352)

`target` cannot be null because `target_sp` is non-null.

lldb/source/Target/RegisterContext.cpp

diff --git a/lldb/source/Target/RegisterContext.cpp b/lldb/source/Target/RegisterContext.cpp
index c4f9c92..f2c038f 100644
--- a/lldb/source/Target/RegisterContext.cpp
+++ b/lldb/source/Target/RegisterContext.cpp
@@ -98,12 +98,8 @@
   uint64_t pc = ReadRegisterAsUnsigned(reg, fail_value);
 
   if (pc != fail_value) {
-    TargetSP target_sp = m_thread.CalculateTarget();
-    if (target_sp) {
-      Target *target = target_sp.get();
-      if (target)
-        pc = target->GetOpcodeLoadAddress(pc, AddressClass::eCode);
-    }
+    if (TargetSP target_sp = m_thread.CalculateTarget())
+      pc = target_sp->GetOpcodeLoadAddress(pc, AddressClass::eCode);
   }
 
   return pc;