Harcode curve in semi-internal modMult function

Saves 80 bytes of code size.
diff --git a/tinycrypt/ecc_dsa.c b/tinycrypt/ecc_dsa.c
index 8462860..2df89a5 100644
--- a/tinycrypt/ecc_dsa.c
+++ b/tinycrypt/ecc_dsa.c
@@ -257,7 +257,7 @@
 	uECC_vli_modSub(z, sum, tx, curve->p, num_words); /* z = x2 - x1 */
 	XYcZ_add(tx, ty, sum, sum + num_words, curve);
 	uECC_vli_modInv(z, z, curve->p, num_words); /* z = 1/z */
-	apply_z(sum, sum + num_words, z, curve);
+	apply_z(sum, sum + num_words, z);
 
 	/* Use Shamir's trick to calculate u1*G + u2*Q */
 	points[0] = 0;
@@ -283,15 +283,15 @@
 		if (point) {
 			uECC_vli_set(tx, point, num_words);
 			uECC_vli_set(ty, point + num_words, num_words);
-			apply_z(tx, ty, z, curve);
+			apply_z(tx, ty, z);
 			uECC_vli_modSub(tz, rx, tx, curve->p, num_words); /* Z = x2 - x1 */
 			XYcZ_add(tx, ty, rx, ry, curve);
-			uECC_vli_modMult_fast(z, z, tz, curve);
+			uECC_vli_modMult_fast(z, z, tz);
 		}
   	}
 
 	uECC_vli_modInv(z, z, curve->p, num_words); /* Z = 1/Z */
-	apply_z(rx, ry, z, curve);
+	apply_z(rx, ry, z);
 
 	/* v = x1 (mod n) */
 	if (uECC_vli_cmp_unsafe(curve->n, rx, num_n_words) != 1) {