Tegra: common: fixup the bl31 code size to be copied at reset

If the CPU doesn't run from BL31_BASE, the firmware needs to be
copied from load address to BL31_BASE during cold boot. The size
should be the actual size of the code, which is indicated by the
__RELA_END__ linker variable.

This patch updates the copy routine to use this variable as a
result.
Signed-off-by: anzhou <anzhou@nvidia.com>
Change-Id: Ie3a48dd54cda1dc152204903d609da3117a0ced9

plat/nvidia/tegra/common/aarch64/tegra_helpers.S

@@ -215,7 +215,8 @@ func plat_reset_handler
 	 */
 	mov	x0, x17
 	mov	x1, x18
-	mov	x2, #BL31_SIZE
+	adr	x2, __RELA_END__
+	sub	x2, x2, x18
 _loop16:
 	cmp	x2, #16
 	b.lo	_loop1