boot: zephyr: migrate to new log subystem

The old log subsystem has been deprecated in Zephyr.
Migrate to the new subsystem to avoid compilation warnings.

In-place log processing is selected as it is required as MCUBoot is
one thread application.

Signed-off-by: Emanuele Di Santo <emdi@nordicsemi.no>
Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>
diff --git a/boot/bootutil/src/bootutil_misc.c b/boot/bootutil/src/bootutil_misc.c
index 75c1dd9..c7c0962 100644
--- a/boot/bootutil/src/bootutil_misc.c
+++ b/boot/bootutil/src/bootutil_misc.c
@@ -33,6 +33,8 @@
 #include "bootutil/enc_key.h"
 #endif
 
+MCUBOOT_LOG_MODULE_DECLARE(mcuboot);
+
 int boot_current_slot;
 
 const uint32_t boot_img_magic[] = {