Staging: emuxx_udc: replace pr_* with dev_*

dev_* is prefered over pr_* when appropriate dev structure is present.
This patch replace pr_info and pr_warn with its dev_ counterpart.

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