regmap: get rid of redundant debugfs_file_{get,put}()

pointless in ->read()/->write() of file_operations used only via
debugfs_create_file()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20250702211602.GC3406663@ZenIV


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>