modules: trusted-firmware-m: Extend kernel header

Add errno.h to the kernel.h used for TF-M builds.

Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>

Author: nordic-krch

modules/trusted-firmware-m/tfm_boards/include/zephyr/kernel.h

@@ -18,6 +18,7 @@
  */
 
 #include <stddef.h>
+#include <errno.h>
 #include <zephyr/sys/__assert.h>
 #include <zephyr/sys/printk.h>
 #include <zephyr/irq.h>