USB: SisUSB2VGA: Convert printk to dev_* macros

This patch convert printk entries to dev_* macros, this provide better
debugging and better readability to the code.

Signed-off-by: Felipe Balbi <felipe.lima@indt.org.br>
Cc: Thomas <thomas@winischhofer.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>