PM: base: power: don't try to use non-existing RTC for storing data

stable inclusion
from stable-5.10.68
commit cd64b416aed2f152d89c25db2ebf4f05e16fc08d
bugzilla: 182671 https://gitee.com/openeuler/kernel/issues/I4EWUH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cd64b416aed2f152d89c25db2ebf4f05e16fc08d



--------------------------------

commit 0560204b upstream.

If there is no legacy RTC device, don't try to use it for storing trace
data across suspend/resume.

Cc: <stable@vger.kernel.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20210903084937.19392-2-jgross@suse.com


Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>