ARM: dts: keystone: Adjust whitespace around '='

Fix whitespace coding style: use single space instead of tabs or
multiple spaces around '=' sign in property assignment.  No functional
changes (same DTB).
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20220526204139.831895-3-krzysztof.kozlowski@linaro.org

arch/arm/boot/dts/keystone-k2g.dtsi

@@ -262,7 +262,7 @@ pmmc: system-controller@2921c00 {
 			 */
 			ti,system-reboot-controller;
 			mbox-names = "rx", "tx";
-			mboxes= <&msgmgr 5 2>,
+			mboxes = <&msgmgr 5 2>,
 				<&msgmgr 0 0>;
 			reg-names = "debug_messages";
 			reg = <0x02921c00 0x400>;