RDMA/usnic: Remove redundant pci_clear_master

Remove pci_clear_master to simplify the code,
the bus-mastering is also cleared in do_pci_disable_device,
like this:
./drivers/pci/pci.c:2197
static void do_pci_disable_device(struct pci_dev *dev)
{
	u16 pci_command;

	pci_read_config_word(dev, PCI_COMMAND, &pci_command);
	if (pci_command & PCI_COMMAND_MASTER) {
		pci_command &= ~PCI_COMMAND_MASTER;
		pci_write_config_word(dev, PCI_COMMAND, pci_command);
	}

	pcibios_disable_device(dev);
}.
And dev->is_busmaster is set to 0 in pci_disable_device.
Signed-off-by: Cai Huoqing <cai.huoqing@linux.dev>
Link: https://lore.kernel.org/r/20230323115742.13836-1-cai.huoqing@linux.devSigned-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/hw/usnic/usnic_ib_main.c

@@ -602,7 +602,6 @@ static int usnic_ib_pci_probe(struct pci_dev *pdev,
 	usnic_vnic_free(vf->vnic);
 out_release_regions:
 	pci_set_drvdata(pdev, NULL);
-	pci_clear_master(pdev);
 	pci_release_regions(pdev);
 out_disable_device:
 	pci_disable_device(pdev);
@@ -623,7 +622,6 @@ static void usnic_ib_pci_remove(struct pci_dev *pdev)
 	kref_put(&pf->vf_cnt, usnic_ib_undiscover_pf);
 	usnic_vnic_free(vf->vnic);
 	pci_set_drvdata(pdev, NULL);
-	pci_clear_master(pdev);
 	pci_release_regions(pdev);
 	pci_disable_device(pdev);
 	kfree(vf);