kselftest/arm64: fix a memleak in zt_regs_run()

If memcmp() does not return 0, "zeros" need to be freed to prevent memleak

Signed-off-by: Ding Xiang <dingxiang@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20230815074915.245528-1-dingxiang@cmss.chinamobile.com


Signed-off-by: Will Deacon <will@kernel.org>