input: qpnp-power-on: set sys_reset_dev to NULL when fail probe

When it failed probe, sys_reset_dev pointed to the area
which will be freed later. So set sys_reset_dev to NULL
when failed probe.

Change-Id: I0a2baad84a355e923356a3e3c14ab007d7ecf63e
Signed-off-by: Maria Yu <aiquny@codeaurora.org>