Documentation/driver-api: Update pcim_enable_device()

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 <phasta@kernel.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20250519112959.25487-4-phasta@kernel.org