Documentation/driver-api: Update pcim_enable_device()

pcim_enable_device() is not related anymore to switching the mode of
operation of any functions. It merely sets up a devres callback for
automatically disabling the PCI device on driver detach.

Adjust the function's documentation.

Signed-off-by: Philipp Stanner <[e-mail]>
Signed-off-by: Krzysztof Wilczyński <[e-mail]>
Reviewed-by: Kuppuswamy Sathyanarayanan <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/driver-api/driver-model/devres.rst

···
   devm_pci_remap_cfgspace()	: ioremap PCI configuration space
   devm_pci_remap_cfg_resource()	: ioremap PCI configuration space resource
 
-  pcim_enable_device()		: after success, some PCI ops become managed
+  pcim_enable_device()		: after success, the PCI device gets disabled automatically on driver detach
   pcim_iomap()			: do iomap() on a single BAR
   pcim_iomap_regions()		: do request_region() and iomap() on multiple BARs
   pcim_iomap_table()		: array of mapped addresses indexed by BAR