r6040: fix all checkpatch errors and warnings

This patch fixes a couple of errors and warnings spotted by checkpatch.pl:
- some lines were over 80 columns
- there were some whitespaces left

The call to printk is now replaced by a call to pr_info and the log-level
included in the driver version is now removed, so there are no longer false
positives on this warning.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: David S. Miller <davem@davemloft.net>