dt-bindings: mmc: sdhci-msm: Clarify register requirements

In sdhci-msm-v5 and beyond, the MCI registers are removed, so there is only
one register region required.

Signed-off-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/sdhci-msm.txt

@@ -25,7 +25,7 @@ Required properties:
 
 - reg: Base address and length of the register in the following order:
 	- Host controller register map (required)
-	- SD Core register map (required)
+	- SD Core register map (required for msm-v4 and below)
 - interrupts: Should contain an interrupt-specifiers for the interrupts:
 	- Host controller interrupt (required)
 - pinctrl-names: Should contain only one value - "default".