docs: debugfs: do not recommend debugfs_remove_recursive

docs: debugfs: do not recommend debugfs_remove_recursive

Update the debugfs documentation to indicate that debugfs_remove()
should be used to clean up debugfs entries.

In commit a3d1e7eb5abe ("simple_recursive_removal(): kernel-side rm -rf
for ramfs-style filesystems"), function debugfs_remove_recursive()
was made into an alias for debugfs_remove():

    #define debugfs_remove_recursive debugfs_remove

Therefore, drivers should just use debugfs_remove() going forward.

Signed-off-by: Timur Tabi <ttabi@nvidia.com>
Link: https://lore.kernel.org/r/20250429173958.3973958-1-ttabi@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>