RDMA/hns: Delete a useless assignment to bond_state

driver inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6Z4E9



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In hns_roce_slave_dec(), bond_state will be changed to
HNS_ROCE_BOND_REGISTERING right before the current main_hr_dev
is being removed from bond group. When the slave decrease
operation is over, bond_state will be changed to
HNS_ROCE_BOND_IS_BONDED in the end of this function. So the
assignment to bond_state in the beginning of the function is
useless and should be deleted.

Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>