Remove trailing whitespace from ecdsa.c

Signed-off-by: Xiaokang Qian <xiaokang.qian@arm.com>
diff --git a/library/ecdsa.c b/library/ecdsa.c
index 40c97ec..355bf89 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -20,7 +20,7 @@
 /*
  * References:
  *
- * SEC1 https://www.secg.org/sec1-v2.pdf 
+ * SEC1 https://www.secg.org/sec1-v2.pdf
  */
 
 #include "common.h"