i40evf: remove unnecessary log messages

We don't need to print log messages when we encounter an out-of-memory
condition, as the allocator will do this for us. Also, remove a Tx hang
message that duplicates the one emitted by the netdev layer, and a
duplicate message in the watchdog.

Change-ID: If2056e6135fe248f66ea939778f9895660f4d189
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>