Attest: Rename useful_buf to q_useful_buf

Set proper namespace to indicate that q_usful_buf
is originated from QCBOR library and to prevent
namespace collison.

Change-Id: I00a10ccc052dd4d4757f1c451d6534385e58ef00
Signed-off-by: Laurence Lundblade <lgl@securitytheory.com>
Co-authored-by: Tamas Ban <tamas.ban@arm.com>
diff --git a/lib/ext/qcbor/inc/UsefulBuf.h b/lib/ext/qcbor/inc/UsefulBuf.h
index 86a7da7..0aaa9b6 100644
--- a/lib/ext/qcbor/inc/UsefulBuf.h
+++ b/lib/ext/qcbor/inc/UsefulBuf.h
@@ -150,7 +150,7 @@
  Eeyore's balloon fits beautifully, "it goes in and out like anything".
 
 */
-typedef struct useful_buf_c {
+typedef struct q_useful_buf_c {
     const void *ptr;
     size_t      len;
 } UsefulBufC;
@@ -161,7 +161,7 @@
  that is to be filled in. The len is the amount of memory,
  not the length of the valid data in the buffer.
  */
-typedef struct useful_buf {
+typedef struct q_useful_buf {
    void  *ptr;
    size_t len;
 } UsefulBuf;