bonding: update the primary for bonding and fix some slight problem

If the primary_slave's name changed, but the bond->prams.primay was still using the old name, it is conflict with the meaning of the primary, so update the primary when the slave change its name.

Do not save the primary when the device is not exist for bonding.

Modify some description for primary in bonding.txt.

Ding Tianhong (4):
bonding: update the primary when slave name changed
bonding: do not save non-existent device to bond primary in check params
bonding: do not save non-existent device to bond primary in sysfs
bonding: update bonding.txt for primary description.

 Documentation/networking/bonding.txt |  3 ++-
 drivers/net/bonding/bond_main.c      | 34 +++++++++++++++++++++++++---------
 drivers/net/bonding/bond_options.c   |  6 ++++++
 3 files changed, 33 insertions(+), 10 deletions(-)

1.8.0