dmaengine: idxd: depends on !UML

Now that UML has PCI support, this driver must depend also on
!UML since it pokes at X86_64 architecture internals that don't
exist on ARCH=um.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Link: https://lore.kernel.org/r/20210625103810.fe877ae0aef4.If240438e3f50ae226f3f755fc46ea498c6858393@changeid
Signed-off-by: Vinod Koul <vkoul@kernel.org>