soc: qcom: mem-offline: fix mem online failure notification

During MEM_GOING_ONLINE, if the hardware memory online fails, notify
the kernel with the failure so that kernel does not online the pages
in this block. Also, on such failures, save the memory states so that
appropriate actions can be taken when MEM_CANCEL_ONLINE event is received.

Change-Id: I9de11b7aeeed857ef7008aff78d19ef237e28a00
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>