rhi: metal: Remove out of date / unneeded comment

E.g. the view.layer thread checker problems are eliminated
for some time now. The other mentioned XCode warning is
likely not there anymore with newer XCode. Whereas the
rest (that we pass validation) should be obvious.

Pick-to: 6.6 6.5
Change-Id: I9754077aa6e178ee2b866b64538991412af5bb5a
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

src/gui/rhi/qrhimetal.mm

@@ -40,13 +40,6 @@ QT_BEGIN_NAMESPACE
 #error ARC not supported
 #endif
 
-// Note: we expect everything here pass the Metal API validation when running
-// in Debug mode in XCode (or with METAL_DEVICE_WRAPPER_TYPE=1). An exception
-// is the nextDrawable Called Early blah blah warning, which is plain and
-// simply false. This may not be present with newer XCode. There may also be
-// warnings about threading (e.g. about accessing view.layer), those are
-// expected for now.
-
 /*!
     \class QRhiMetalInitParams
     \inmodule QtRhi