can: pch_can: use generic power management

can: pch_can: use generic power management

Drivers using legacy power management .suspen()/.resume() callbacks have to
manage PCI states and device's PM states themselves. They also need to take
care of standard configuration registers.

Switch to generic power management framework using a single "struct dev_pm_ops"
variable to take the unnecessary load from the driver. This also avoids the
need for the driver to directly call most of the PCI helper functions and
device power state control functions, as through the generic framework PCI Core
takes care of the necessary operations, and drivers are required to do only
device-specific jobs.

Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Link: https://lore.kernel.org/r/20200728085757.888620-1-vaibhavgupta40@gmail.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>