ARM: dts: exynos: Fix IOMMU support for GScaler devices on Exynos5250

ARM: dts: exynos: Fix IOMMU support for GScaler devices on Exynos5250

BugLink: http://bugs.launchpad.net/bugs/1773233
commit 6f4870753f29edf7dc39444246f9e39987b8b158 upstream.

The proper name for the property, which assign given device to IOMMU is
'iommus', not 'iommu'. Fix incorrect name and let all GScaler devices
to be properly handled when IOMMU support is enabled.

Reported-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: 6cbfdd73a94f ("ARM: dts: add sysmmu nodes for exynos5250")
Cc: <stable@vger.kernel.org> # v4.8+
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>