video: exynos_fimd: Add framework to disable FIMD sysmmu

On Exynos5420 and newer versions, the FIMD sysmmus are in
"on state" by default.
We have to disable them in order to make FIMD DMA work.
This patch adds the required framework to exynos_fimd driver,
and disables FIMD sysmmu on Exynos5420.

Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
diff --git a/doc/device-tree-bindings/video/exynos-fb.txt b/doc/device-tree-bindings/video/exynos-fb.txt
index bb7441c..dc4e44f 100644
--- a/doc/device-tree-bindings/video/exynos-fb.txt
+++ b/doc/device-tree-bindings/video/exynos-fb.txt
@@ -55,6 +55,12 @@
 	samsung,pclk-name: parent clock identifier: 1(MPLL), 2(EPLL), 3(VPLL)
 	samsung,sclk-div: parent_clock/source_clock ratio
 	samsung,dual-lcd-enabled: 1 if you support two LCD, else 0
+	samsung,disable-sysmmu: Define this if you want to disable FIMD sysmmu.
+				(needed for Exynos5420 and newer versions)
+				Add the required FIMD sysmmu nodes to be
+				disabled with compatible string
+				"samsung,sysmmu-v3.3", with a "reg" property
+				holding the register address of FIMD sysmmu.
 
 Example:
 SOC specific part: