usb: Convert pr_warning to pr_warn

Use the more common logging mechanism.

Miscellanea:

o Realign multiline statements
o Coalesce format

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>