forked from Mirrors/opensbi

Before entering _scratch_init(), register t3 already holds a copy of the firmware end address, hence there is no need to calculate it again. This reduces 3 instructions in each _scratch_init() loop. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Xiang W <wxjstz@126.com> Reviewed-by: Atish Patra <atish.patra@wdc.com>