Avoid duplicate program names

Visual Studio and CMake didn't like having targets with the same name,
albeit in different directories.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/programs/hash/CMakeLists.txt b/programs/hash/CMakeLists.txt
index 9ff1df1..da98188 100644
--- a/programs/hash/CMakeLists.txt
+++ b/programs/hash/CMakeLists.txt
@@ -1,7 +1,7 @@
 set(executables
     generic_sum
     hello
-    hmac_demo
+    md_hmac_demo
 )
 
 foreach(exe IN LISTS executables)
diff --git a/programs/hash/hmac_demo.c b/programs/hash/md_hmac_demo.c
similarity index 100%
rename from programs/hash/hmac_demo.c
rename to programs/hash/md_hmac_demo.c