igb: Update max_frame_size to account for an optional VLAN tag if present

igb: Update max_frame_size to account for an optional VLAN tag if present

This patch modifies the max_frame_size in order account for an optional
VLAN tag.  In order to support this we must also increase the
MAX_STD_JUMBO_FRAME_SIZE to account for the 4 extra bytes.

(cherry picked from commit 153285f9ce88b2d37e29a351dfcf7601ff274c69)
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by:  Aaron Brown  <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Joe Jin <joe.jin@oracle.com>