ARM: tegra{20,30}: Rename "mc" to "memory-controller"

Use a more plain english name.

Signed-off-by: Hiroshi DOYU <[e-mail]>
[swarren: remove redundant unit address from Tegra30 example]
Signed-off-by: Stephen Warren <[e-mail]>

Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-mc.txt

···
 - interrupts : Should contain MC General interrupt.
 
 Example:
-	mc {
+	memory-controller@0x7000f000 {
 		compatible = "nvidia,tegra20-mc";
 		reg = <0x7000f000 0x024
 		       0x7000f03c 0x3c4>;

Documentation/devicetree/bindings/arm/tegra/nvidia,tegra30-mc.txt

···
 - interrupts : Should contain MC General interrupt.
 
 Example:
-	mc {
+	memory-controller {
 		compatible = "nvidia,tegra30-mc";
 		reg = <0x7000f000 0x010
 		       0x7000f03c 0x1b4