staging: rtl8192e: use generic power management

staging: rtl8192e: use generic power management

The structure of working of PM hooks for source files is:
    drivers/staging/rtl8192e/rtl8192e/rtl_pm.h   : callbacks declared
    drivers/staging/rtl8192e/rtl8192e/rtl_pm.c   : callbacks defined
    drivers/staging/rtl8192e/rtl8192e/rtl_core.c : callbacks used

Drivers should not use legacy power management as they have to manage power
states and related operations, for the device, themselves. This driver was
handling them with the help of PCI helper functions like
pci_save/restore_state(), pci_enable/disable_device(), etc.

With generic PM, all essentials will be handled by the PCI core. Driver
needs to do only device-specific operations.

The driver was also using pci_enable_wake(...,..., 0) to disable wake. Use
device_wakeup_disable() instead. Use device_set_wakeup_enable() where WOL
is decided by the value of a variable during runtime.

Compile-tested only.

Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Link: https://lore.kernel.org/r/20200629082819.216405-3-vaibhavgupta40@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>