um: Fix IPC on um

commit c1d7e01d (ipc: use Kconfig options for __ARCH_WANT_[COMPAT_]IPC_PARSE_VERSION)
forgot UML and broke IPC on it.
Also UML has to select ARCH_WANT_IPC_PARSE_VERSION usin Kconfig.

Reported-and-tested-by: &lt;Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Richard Weinberger <richard@nod.at>