Revert "Merge pull request #49 from mbolivar/flash-map-updates"

This reverts commit a52d7a21f01bd2859be9e62e20cbe029dc5e846c, reversing
changes made to d21abaaa35c31d88f9b4a18f82bce848adffb569.

Premature merge.  Will bring this back in after #41 merges.
diff --git a/apps/boot/src/boot.c b/apps/boot/src/boot.c
index 0a26edb..fbc4b7d 100755
--- a/apps/boot/src/boot.c
+++ b/apps/boot/src/boot.c
@@ -47,7 +47,6 @@
 main(void)
 {
     struct boot_rsp rsp;
-    uintptr_t flash_base;
     int rc;
 
 #if MYNEWT_VAL(BOOT_SERIAL)
@@ -71,11 +70,7 @@
     rc = boot_go(&rsp);
     assert(rc == 0);
 
-    rc = flash_device_base(rsp->br_flash_dev_id, &flash_base);
-    assert(rc == 0);
-
-    hal_system_start((void *)(flash_base + rsp.br_image_off +
-                              rsp.br_hdr->ih_hdr_size));
+    hal_system_start((void *)(rsp.br_image_addr + rsp.br_hdr->ih_hdr_size));
 
     return 0;
 }