Remove unneeded include

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/include/mbedtls/constant_time.h b/include/mbedtls/constant_time.h
index 69df954..bd7758f 100644
--- a/include/mbedtls/constant_time.h
+++ b/include/mbedtls/constant_time.h
@@ -20,8 +20,6 @@
 #ifndef MBEDTLS_CONSTANT_TIME_H
 #define MBEDTLS_CONSTANT_TIME_H
 
-#include "common.h"
-
 #include <stddef.h>