Removes f_rng from mbedtls_rsa_rsassa_pkcs1_v15_verify

Commit performs removal of f_rng parameter
from mbedtls_rsa_rsassa_pkcs1_v15_verify
function in preparation for removal of mode
parameter.

Signed-off-by: Thomas Daubney <thomas.daubney@arm.com>
diff --git a/library/rsa.c b/library/rsa.c
index 9e2d054..4d56970 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -2331,7 +2331,6 @@
  * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-v1_5-VERIFY function
  */
 int mbedtls_rsa_rsassa_pkcs1_v15_verify( mbedtls_rsa_context *ctx,
-                                 int (*f_rng)(void *, unsigned char *, size_t),
                                  int mode,
                                  mbedtls_md_type_t md_alg,
                                  unsigned int hashlen,
@@ -2376,7 +2375,7 @@
 
     ret = ( mode == MBEDTLS_RSA_PUBLIC )
           ? mbedtls_rsa_public(  ctx, sig, encoded )
-          : mbedtls_rsa_private( ctx, f_rng, NULL, sig, encoded );
+          : mbedtls_rsa_private( ctx, NULL, NULL, sig, encoded );
     if( ret != 0 )
         goto cleanup;
 
@@ -2428,7 +2427,7 @@
     {
 #if defined(MBEDTLS_PKCS1_V15)
         case MBEDTLS_RSA_PKCS_V15:
-            return mbedtls_rsa_rsassa_pkcs1_v15_verify( ctx, NULL, MBEDTLS_RSA_PUBLIC, md_alg,
+            return mbedtls_rsa_rsassa_pkcs1_v15_verify( ctx, MBEDTLS_RSA_PUBLIC, md_alg,
                                                 hashlen, hash, sig );
 #endif