Merge branch 'bridge_mode'

Roopa Prabhu says:

====================
remove bridge mode BRIDGE_MODE_SWDEV

BRIDGE_MODE_SWDEV was introduced to indicate switchdev offloads
for bridging from user space (In other words to call into the hw switch
port driver directly). But user can use existing BRIDGE_FLAGS_SELF
to call into the hw switch port driver today. swdev mode is not required
anymore. So, this patch removes it.

v4 - v5
    incorporate comments
    - Define BRIDGE_MODE_UNDEF to handle cases where mode is not defined
    - reverse the order of patches
    - include patch comments in all patches
====================

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>