ARM: dts: bcm2835-rpi-zero-w: Fix bus-width of sdhci

The commit e7774049ff25 ("ARM: dts: bcm283x: Define MMC interfaces at
board level") accidently dropped the bus width for the sdhci on the
RPi Zero W, because the board file was relying on the defaults
from bcm2835-rpi.dtsi. So fix this performance regression by adding
the bus width to the board file.

Fixes: e7774049ff25 ("ARM: dts: bcm283x: Define MMC interfaces at board level")
Reported-by: Phil Elwell <[e-mail]>
Signed-off-by: Stefan Wahren <[e-mail]>
Signed-off-by: Florian Fainelli <[e-mail]>

arch/arm/boot/dts/bcm2835-rpi-zero-w.dts

···
 	#address-cells = <1>;
 	#size-cells = <0>;
 	pinctrl-0 = <&emmc_gpio34 &gpclk2_gpio43>;
+	bus-width = <4>;
 	mmc-pwrseq = <&wifi_pwrseq>;
 	non-removable;
 	status = "okay";