env: flash: Cosmetic fix

Change tab to space in env_flash_init().

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>

env/flash.c

@@ -228,7 +228,7 @@ static int env_flash_init(void)
 		return 0;
 	}
 
-	gd->env_valid	= ENV_INVALID;
+	gd->env_valid = ENV_INVALID;
 	return 0;
 }
 #endif