driver core: Clarify that dev_err_probe() is OK even w/out -EPROBE_DEFER

driver core: Clarify that dev_err_probe() is OK even w/out -EPROBE_DEFER

There is some debate about whether it's deemed acceptable to call
dev_err_probe() if you know that the error code can never be
-EPROBE_DEFER. Clarify in the function comments that this is
OK. Specifically this makes us able to transform code like this:

  ret = do_something_that_cant_defer();
  if (ret < 0) {
    dev_err(dev, "The foo failed to bar (%pe)\n", ERR_PTR(ret));
    return ret;
  }

to code like this:
  ret = do_something_that_cant_defer();
  if (ret < 0)
    return dev_err_probe(dev, ret, "The foo failed to bar\n");

It is also possible that in the future folks might want a CONFIG
option to strip out all probe error strings to save space (keeping
non-probe errors) with the argument that probe errors rarely happen
after bringup. Having probe errors reported with a consistent function
would allow that.

Cc: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20210916161931.1.I32bea713bd6c6fb419a24da73686145742b6c117@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>