CVE-2026-72453: regcache: Do not overwrite error code when finalizing cache after error

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

regcache: Do not overwrite error code when finalizing cache after error

During regcache initialization, if an error occurs in the cacheops->populate callback, and if cache operations include an exit callback, the error code from populate() is overwritten with the return value from exit(). This hides the error condition from the caller of regcacheinit(), and can cause NULL pointer dereferences when the regcache is later accessed.