xen/pciback: fix cast to restricted pci_ers_result_t and pci_power_t

This patch fix the following sparse warning by applying
__force cast to pci_ers_result_t and pci_power_t.

drivers/xen/xen-pciback/pci_stub.c:760:16: sparse: warning: cast to restricted pci_ers_result_t
drivers/xen/xen-pciback/conf_space_capability.c:125:22: sparse: warning: cast to restricted pci_power_t

No functional changes intended.
Signed-off-by: Min-Hua Chen <minhuadotchen@gmail.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Message-ID: <20240917233653.61630-1-minhuadotchen@gmail.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

drivers/xen/xen-pciback/conf_space_capability.c

@@ -122,7 +122,7 @@ static int pm_ctrl_write(struct pci_dev *dev, int offset, u16 new_value,
 	if (err)
 		goto out;
 
-	new_state = (pci_power_t)(new_value & PCI_PM_CTRL_STATE_MASK);
+	new_state = (__force pci_power_t)(new_value & PCI_PM_CTRL_STATE_MASK);
 
 	new_value &= PM_OK_BITS;
 	if ((old_value & PM_OK_BITS) != new_value) {

drivers/xen/xen-pciback/pci_stub.c

@@ -821,7 +821,7 @@ static pci_ers_result_t common_process(struct pcistub_device *psdev,
 	}
 	clear_bit(_PCIB_op_pending, (unsigned long *)&pdev->flags);
 
-	res = (pci_ers_result_t)aer_op->err;
+	res = (__force pci_ers_result_t)aer_op->err;
 	return res;
 }