common/Kconfig: fix comments syntax error

Fix comments error in EVENT_DEBUG description:
    this get usefui -> this to get useful

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/common/Kconfig b/common/Kconfig
index 6345d5c..a19d82f 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -626,7 +626,7 @@
 	bool "Enable event debugging assistance"
 	default y if SANDBOX
 	help
-	  Enable this get usefui features for seeing what is happening with
+	  Enable this to get useful features for seeing what is happening with
 	  events, such as event-type names. This adds to the code size of
 	  U-Boot so can be turned off for production builds.