iommu: Rename iommu_get_instance()

iommu: Rename iommu_get_instance()

Rename the function to iommu_ops_from_fwnode(), because that
is what the function actually does. The new name is much
more descriptive about what the function does.

BugLink: http://bugs.launchpad.net/bugs/1688158
Signed-off-by: Joerg Roedel <jroedel@suse.de>
(cherry picked from commit 534766dfef999f7e7349bbd91cd19c1673792af3)
Signed-off-by: Manoj Iyer <manoj.iyer@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>