soc: qcom: SSR: Fix registration order for wakeup source

wakeup_source_register() expects a registered struct device *.
But in the subsys_register() path, device_register() is called
after wakeup_source_register(), which is incorrect. Hence,
flip the order of registrations. Also as an extension, reorder
the error-handling path of subsys_register() and the cleanup
sequence in subsys_unregister().

Change-Id: I976951ddcf5635ec7931253bfcda834ef30c3898
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>