zephyr: io: include 'bootutil_log.h' and declare log module membership

This fixes below error when building with 'MCUBOOT_INDICATION_LED' and
'LOG' enabled:

  In file included from zephyr/include/zephyr/logging/log.h:11,
                   from zephyr/include/zephyr/usb/usb_device.h:43,
                   from bootloader/mcuboot/boot/zephyr/io.c:26:
  mcuboot/boot/zephyr/io.c: In function 'io_led_init':
  zephyr/include/zephyr/logging/log_core.h:151:20: error:
    '__log_level' undeclared (first use in this function)
    151 |         (_level <= __log_level) &&                                          \
        |                    ^~~~~~~~~~~

Fixes: 433b8480 ("zephyr: Move IO functions out of main to separate file")
Signed-off-by: Piotr Dymacz <pepe2k@gmail.com>
diff --git a/boot/zephyr/io.c b/boot/zephyr/io.c
index fc1966d..e6d54d3 100644
--- a/boot/zephyr/io.c
+++ b/boot/zephyr/io.c
@@ -28,6 +28,7 @@
 #include <zephyr/linker/linker-defs.h>
 
 #include "target.h"
+#include "bootutil/bootutil_log.h"
 
 #if defined(CONFIG_BOOT_SERIAL_PIN_RESET) || defined(CONFIG_BOOT_FIRMWARE_LOADER_PIN_RESET)
 #include <zephyr/drivers/hwinfo.h>
@@ -78,6 +79,8 @@
 #error "Unsupported board: led0 devicetree alias is not defined"
 #endif
 
+BOOT_LOG_MODULE_DECLARE(mcuboot);
+
 void io_led_init(void)
 {
     if (!device_is_ready(led0.port)) {