Add profile macro calls

This matches the calls in firmware version 0037.

BUG=none
TEST=manual

Review URL: http://codereview.chromium.org/3859002

Change-Id: I3b45051dec3f4f45414802b39122c8d52c4d62f1
diff --git a/firmware/lib/vboot_kernel.c b/firmware/lib/vboot_kernel.c
index 3369b6d..8ee45a7 100644
--- a/firmware/lib/vboot_kernel.c
+++ b/firmware/lib/vboot_kernel.c
@@ -325,12 +325,15 @@
       }
 
       /* Read the kernel data */
+      VBPERFSTART("VB_RKD");
       if (0 != BootDeviceReadLBA(part_start + body_offset_sectors,
                                  body_sectors,
                                  params->kernel_buffer)) {
         VBDEBUG(("Unable to read kernel data.\n"));
+        VBPERFEND("VB_RKD");
         goto bad_kernel;
       }
+      VBPERFEND("VB_RKD");
 
       /* Verify kernel data */
       if (0 != VerifyData((const uint8_t*)params->kernel_buffer,