i40evf: clean up log message formatting

Clean up inconsistent log messages, mostly related to punctuation. Based
on the dogma that "kernel messages are not sentences", remove all
trailing periods. Reword a few of the messages to make them less
sentence-like.

Change-ID: Ibd849aa7623a77549b0709988c66ab05d1311472
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>