i40evf: pass struct virtchnl_filter by reference rather than by value

Passing struct virtchnl_filter f by value requires a 272 byte copy
on x86_64, so instead pass it by reference is much more efficient. Also
adjust some lines that are over 80 chars.

Detected by CoverityScan, CID#1465285 ("Big parameter passed by value")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Harshitha Ramamurthy <harshitha.ramamurthy@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>