xen: Kconfig: Fix spelling mistake "Maxmium" -> "Maximum"

There is a spelling mistake in a Kconfig description. Fix it.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20221007203500.2756787-1-colin.i.king@gmail.com


Signed-off-by: Juergen Gross <jgross@suse.com>