Staging: emxx_udc: Replace custom printk macro ERR with dev_err or pr_err

This patch removes the use of custom printk macros ERR and replace it
with dev_err, or pr_err in the following cases:
- if no appropriate struct device *dev field where found for dev_err.
- or dev could be null eg. "dev_err(udc->dev" not possible inside "if
  (udc == null)"
Issue addressed by checkpatch.pl.

Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>