Assign have_rng in declaration of ecp_mul_mxz

Signed-off-by: Agathiyan Bragadeesh <agathiyan.bragadeesh2@arm.com>
diff --git a/library/ecp.c b/library/ecp.c
index 1cf242a..5b60291 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -2593,7 +2593,7 @@
                        void *p_rng)
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
-    int have_rng;
+    int have_rng = 1;
     size_t i;
     unsigned char b;
     mbedtls_ecp_point RP;
@@ -2626,9 +2626,8 @@
     /* RP.X might be slightly larger than P, so reduce it */
     MOD_ADD(RP.X);
 
-    /* Randomize coordinates of the starting point */
-    have_rng = 1;
 #if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
+    /* Derandomize coordinates of the starting point */
     if (f_rng == NULL) {
         have_rng = 0;
     }