Jit: Re-add dcbx masking

When making 92d1d60, I checked whether the ~0x1f masking in dcbx
actually was necessary. I came to the conclusion that it wasn't,
so I removed it. However, I hadn't checked the second half of
InvalidateICache closely enough - the masking is actually needed.

This commit re-adds the masking, but this time in C++ code instead
of in jitted code in order to save icache. Though I suppose the
difference doesn't matter all that much, since this is in farcode
and all...

Hopefully fixes https://bugs.dolphin-emu.org/issues/12612.

Source/Core/Core/PowerPC/JitInterface.cpp

@@ -224,6 +224,11 @@ void InvalidateICache(u32 address, u32 size, bool forced)
     g_jit->GetBlockCache()->InvalidateICache(address, size, forced);
 }
 
+void InvalidateICacheLine(u32 address)
+{
+  InvalidateICache(address & ~0x1f, 32, false);
+}
+
 void CompileExceptionCheck(ExceptionType type)
 {
   if (!g_jit)