boot: boot_serial: Fix wrong cbor type for confirm

Fixes the wrong variable type being used for the confirm element.

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

boot/boot_serial/src/boot_serial.c

@@ -432,7 +432,7 @@ bs_set(char *buf, int len)
  zcbor_new_state(zsd, sizeof(zsd) / sizeof(zcbor_state_t), (uint8_t *)buf, len, 1);
 
  struct zcbor_map_decode_key_val image_set_state_decode[] = {
- ZCBOR_MAP_DECODE_KEY_DECODER("confirm", zcbor_uint32_decode, &confirm),
+ ZCBOR_MAP_DECODE_KEY_DECODER("confirm", zcbor_bool_decode, &confirm),
 #ifdef MCUBOOT_SERIAL_IMG_GRP_HASH
  ZCBOR_MAP_DECODE_KEY_DECODER("hash", zcbor_bstr_decode, &img_hash),
 #endif