Move #include "common.h" where config.h used to be

After removing config.h, the inclusion of it in common.h would be too late
in the code. Therefore common.h has been moved to where config.h used to
be included.

Signed-off-by: Joe Subbiani <joe.subbiani@arm.com>
diff --git a/library/psa_its_file.c b/library/psa_its_file.c
index 08503f2..c4782cd 100644
--- a/library/psa_its_file.c
+++ b/library/psa_its_file.c
@@ -18,6 +18,8 @@
  *  limitations under the License.
  */
 
+#include "common.h"
+
 #if defined(MBEDTLS_PSA_ITS_FILE_C)
 
 #if defined(MBEDTLS_PLATFORM_C)
@@ -32,8 +34,6 @@
 
 #include "psa_crypto_its.h"
 
-#include "common.h"
-
 #include <limits.h>
 #include <stdint.h>
 #include <stdio.h>