RDMA/hns: Improve readability of check_bond_support()

driver inclusion
category: cleanup
bugzilla: https://gitee.com/openeuler/kernel/issues/I8LY0D



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Extract linking check and unlinking check into 2 functions from
check_bond_support() to improve readability.

Fixes: 6ba084e0 ("RDMA/hns: add constraints for bonding-unsupported situations")
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>