USB: OHCI: make ohci-platform use dev_err() instead of pr_err()

This patch converts the ohci-platform driver to use dev_err() functions
instead of pr_err().

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>