ARM: dts: imx7d: Specify viewport count for PCIE block

i.MX7D comes with 4 viewports, so configure PCIE node accordingly so
that the driver won't assume we only have 2.

Signed-off-by: Andrey Smirnov <[e-mail]>
Cc: Richard Zhu <[e-mail]>
Cc: Chris Healy <[e-mail]>
Cc: Lucas Stach <[e-mail]>
Cc: Fabio Estevam <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Reviewed-by: Lucas Stach <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

arch/arm/boot/dts/imx7d.dtsi

···
 		ranges = <0x81000000 0 0          0x4ff80000 0 0x00010000   /* downstream I/O */
 			  0x82000000 0 0x40000000 0x40000000 0 0x0ff00000>; /* non-prefetchable memory */
 		num-lanes = <1>;
+		num-viewport = <4>;
 		interrupts = <GIC_SPI 122 IRQ_TYPE_LEVEL_HIGH>;
 		interrupt-names = "msi";
 		#interrupt-cells = <1>;