Staging: lustre: obdclass: obdo: Declare iattr_from_obdo as static

Declare iattr_from_obdo as static since it is used only in this
particular file.Also remove the corresponding declaration from
header file.

Signed-off-by: Shraddha Barke <shraddha.6596@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>