dfu: boot: mcuboot: Use Kconfig for log level

Prevents this module from just trampling over your logging with
debug logs no matter the configuration

Signed-off-by: Jamie McCrae <spam@helper3000.net>
diff --git a/subsys/dfu/boot/mcuboot.c b/subsys/dfu/boot/mcuboot.c
index cdea2ab..f6122e3 100644
--- a/subsys/dfu/boot/mcuboot.c
+++ b/subsys/dfu/boot/mcuboot.c
@@ -46,7 +46,7 @@
 
 #include "mcuboot_priv.h"
 
-LOG_MODULE_REGISTER(mcuboot_dfu, LOG_LEVEL_DBG);
+LOG_MODULE_REGISTER(mcuboot_dfu, CONFIG_IMG_MANAGER_LOG_LEVEL);
 
 /*
  * Helpers for image headers and trailers, as defined by mcuboot.