test_suite_ecp: Fixed curve bit-length.

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index 16f5f8c..819d527 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -1324,8 +1324,8 @@
 #endif
 #if defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED) && defined(MBEDTLS_ECP_NIST_OPTIM)
         case MBEDTLS_ECP_DP_SECP521R1:
-            limbs = BITS_TO_LIMBS(522) * 2;
-            curve_bits = 522;
+            limbs = BITS_TO_LIMBS(521) * 2;
+            curve_bits = 521;
             curve_func = &mbedtls_ecp_mod_p521_raw;
             break;
 #endif