boot/bootutil: added log on swap type used

Added LOG for informing which a swap type is performed.

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>
diff --git a/boot/bootutil/src/swap_move.c b/boot/bootutil/src/swap_move.c
index f968fae..6f33982 100644
--- a/boot/bootutil/src/swap_move.c
+++ b/boot/bootutil/src/swap_move.c
@@ -449,6 +449,8 @@
     const struct flash_area *fap_sec;
     int rc;
 
+    BOOT_LOG_INF("Starting swap using move algorithm.");
+
     sz = 0;
     g_last_idx = 0;
 
@@ -480,6 +482,9 @@
 
         if (g_last_idx >= first_trailer_idx) {
             BOOT_LOG_WRN("Not enough free space to run swap upgrade");
+            BOOT_LOG_WRN("required %d bytes but only %d are available",
+                         (g_last_idx + 1) * sector_sz ,
+                         first_trailer_idx * sector_sz);
             bs->swap_type = BOOT_SWAP_TYPE_NONE;
             return;
         }