SRIOV doesn't implement PMC capability of PCIe, so it can't update
power state by reading PMC register.

Currently, amdgpu driver doesn't disable pci device when removing
driver, the enable_cnt of pci device will not be decrease to 0.
When reloading driver, pci_enable_device will do nothing as
enable_cnt is not zero. And power state will not be updated as PMC
is not support.
So current_state of pci device is not D0 state and pci_enable_msi
return fail.

Add pci_disable_device when remmoving driver to fix the issue.
Signed-off-by: NXiangliang.Yu <Xiangliang.Yu@amd.com>
Acked-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>