soc: litex: Remove duplicated header file inclusion

The header file <linux/errno.h> is already included above and can be
removed here.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Mateusz Holenko <mholenko@antmicro.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

drivers/soc/litex/litex_soc_ctrl.c

@@ -13,7 +13,6 @@
 #include <linux/platform_device.h>
 #include <linux/printk.h>
 #include <linux/module.h>
-#include <linux/errno.h>
 #include <linux/io.h>
 #include <linux/reboot.h>