Revert "x86: disable IOMMUs on kernel crash"

Revert "x86: disable IOMMUs on kernel crash"

commit 8f9f55e83e939724490d7cde3833c4883c6d1310 upstream.

This effectively reverts commit 61d047be99757fd9b0af900d7abce9a13a337488.

Disabling the IOMMU can potetially allow DMA transactions to
complete without being translated.  Leave it enabled, and allow
crash kernel to do the IOMMU reinitialization properly.

Cc: Joerg Roedel <joerg.roedel@amd.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>