staging/vme: Use pr_ printks in vme_pio2_core.c

The below checkpatch warnings was fixed,

-WARNING: Prefer pr_err(... to printk(KERN_ERR, ...

and added pr_fmt.

Signed-off-by: Toshiaki Yamane <yamanetoshi@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>