RDMA/hfi1: Depend on !UML

Both hfi1 and UML depend on x86_64, this can trigger build errors.
This driver must depends on !UML because it accesses x86_64
features that are not supported by UML.

Link: https://lore.kernel.org/r/165755127879.2996325.5668395672492732376.stgit@awfm-02.cornelisnetworks.com


Signed-off-by: Ehab Ababneh <ehab.ababneh@cornelisnetworks.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>