[SCSI] csiostor: Use pcie_capability_clear_and_set_word() to simplify code

pci_is_pcie() and pcie_capability_clear_and_set_word() make it trivial
to set the PCIe Completion Timeout, so just fold the
csio_set_pcie_completion_timeout() function into its caller.

[bhelgaas: changelog, fold csio_set_pcie_completion_timeout() into caller]
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Naresh Kumar Inna <naresh@chelsio.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jesper Juhl <jj@chaosbits.net>