CVE-2024-35247: fpga: region: add owner module and take its refcount

In the Linux kernel, the following vulnerability has been resolved:

fpga: region: add owner module and take its refcount

The current implementation of the fpga region assumes that the low-level module registers a driver for the parent device and uses its owner pointer to take the module's refcount. This approach is problematic since it can lead to a null pointer dereference while attempting to get the region during programming if the parent device does not have a driver.

To address this problem, add a module owner pointer to the fpgaregion struct and use it to take the module's refcount. Modify the functions for registering a region to take an additional owner module parameter and rename them to avoid conflicts. Use the old function names for helper macros that automatically set the module that registers the region as the owner. This ensures compatibility with existing low-level control modules and reduces the chances of registering a region without setting the owner.

Also, update the documentation to keep it consistent with the new interface for registering an fpga region.