nl_bond: change API to reflect STP setting; only set state in the case that bridge is stp_state > 0
nl_bond: change API to reflect STP setting; only set state in the case that bridge is stp_state > 0

Signed-off-by: Rubens Figueiredo <22177f75c46bd149db738f8a1dfeab4c8cbd2d82@bisdn.de>

bisdn/basebox,bisdn/basebox,bisdn/basebox,bisdn/basebox