Drivers using legacy PM have to manage PCI states and device's PM states
themselves. They also need to take care of configuration registers.

With improved and powerful support of generic PM, PCI Core takes care of
above mentioned, device-independent, jobs.

The callbacks make use of PCI helper functions like
pci_save/restore_state(), pci_enable/disable_device() and
pci_set_power_state() to do required operations. In generic mode, they are
no longer needed.

Change function parameter in both .suspend() and .resume() to
"struct device*" type. Use dev_get_drvdata() to get drv data.

The .suspend() callback is invoking rt2x00lib_suspend() which needs to be
modified as generic rt2x00pci_suspend() has no pm_message_t type argument,
passed to it, which is required by it according to its declaration.
Although this variable remained unused in the function body. Hence, remove
it from the function definition & declaration.

rt2x00lib_suspend() is also invoked by rt2x00usb_suspend() and
rt2x00soc_suspend(). Thus, modify the functional call accordingly in their
function body.

Earlier, .suspend() & .resume() were exported and were used by the
following drivers:
    - drivers/net/wireless/ralink/rt2x00/rt2400pci.c
    - drivers/net/wireless/ralink/rt2x00/rt2500pci.c
    - drivers/net/wireless/ralink/rt2x00/rt2800pci.c
    - drivers/net/wireless/ralink/rt2x00/rt61pci.c

Now, we only need to bind "struct dev_pm_ops" variable to
"struct pci_driver". Thus, make the callbacks static. Declare an
"extern const struct dev_pm_ops" variable and bind PM callbacks to it. Now,
export the variable instead and use it in respective drivers.

Compile-tested only.
Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200717110928.454867-1-vaibhavgupta40@gmail.com