zephyr: migrate includes to <zephyr/...>

Zephyr has prefixed all of its includes with <zephyr/...>. While the
_old_ mode can still be used (CONFIG_LEGACY_INCLUDE_PATH) and is still
enabled by default, it's better to be prepared for its removal in the
future.

Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>
diff --git a/boot/zephyr/arm_cleanup.c b/boot/zephyr/arm_cleanup.c
index c6f738b..d58956f 100644
--- a/boot/zephyr/arm_cleanup.c
+++ b/boot/zephyr/arm_cleanup.c
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#include <arch/arm/aarch32/cortex_m/cmsis.h>
-#include <toolchain.h>
+#include <zephyr/arch/arm/aarch32/cortex_m/cmsis.h>
+#include <zephyr/toolchain.h>
 
 #if CONFIG_CPU_HAS_NXP_MPU
 #include <fsl_sysmpu.h>