tls: P256: do not open-code copying of struct variables

function                                             old     new   delta
sp_256_ecc_mulmod_8                                  536     534      -2

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/tls_sp_c32.c b/networking/tls_sp_c32.c
index d09f7e8..29dd042 100644
--- a/networking/tls_sp_c32.c
+++ b/networking/tls_sp_c32.c
@@ -1361,13 +1361,13 @@
 		dump_512("t[1].y %s\n", t[1].y);
 		dump_512("t[1].z %s\n", t[1].z);
 		dbg("t[2] = t[%d]\n", y);
-		memcpy(&t[2], &t[y], sizeof(sp_point));
+		t[2] = t[y]; /* struct copy */
 		dbg("t[2] *= 2\n");
 		sp_256_proj_point_dbl_8(&t[2], &t[2]);
 		dump_512("t[2].x %s\n", t[2].x);
 		dump_512("t[2].y %s\n", t[2].y);
 		dump_512("t[2].z %s\n", t[2].z);
-		memcpy(&t[y], &t[2], sizeof(sp_point));
+		t[y] = t[2]; /* struct copy */
 
 		n <<= 1;
 		c--;