drm/nouveau/pci: Move an expression into a function call parameter in nvkm_pcie_set_link()

The variable “pbus” was read only once in the implementation of
the function “nvkm_pcie_set_link”.
Thus move the usage of an expression into a parameter for a function call.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/04e2c1f5-26c7-9a23-5861-3d8757556cdd@web.de

drivers/gpu/drm/nouveau/nvkm/subdev/pci/pcie.c

@@ -116,12 +116,10 @@ nvkm_pcie_set_link(struct nvkm_pci *pci, enum nvkm_pcie_speed speed, u8 width)
 {
 	struct nvkm_subdev *subdev;
 	enum nvkm_pcie_speed cur_speed, max_speed;
-	struct pci_bus *pbus;
 	int ret;
 
 	if (!pci || !pci_is_pcie(pci->pdev))
 		return 0;
-	pbus = pci->pdev->bus;
 
 	if (!pci->func->pcie.set_link)
 		return -ENOSYS;
@@ -135,7 +133,7 @@ nvkm_pcie_set_link(struct nvkm_pci *pci, enum nvkm_pcie_speed speed, u8 width)
 	}
 
 	cur_speed = pci->func->pcie.cur_speed(pci);
-	max_speed = min(nvkm_pcie_speed(pbus->max_bus_speed),
+	max_speed = min(nvkm_pcie_speed(pci->pdev->bus->max_bus_speed),
 			pci->func->pcie.max_speed(pci));
 
 	nvkm_trace(subdev, "current speed: %s\n", nvkm_pcie_speeds[cur_speed]);