habanalabs: prevent false heartbeat failure during soft-reset

The heartbeat thread is active during soft-reset, and it tries to send
messages to CPU-CP core.
Within the soft-reset, in the time window in which the device is marked
as disabled, any CPU-CP command is "silently" skipped and a success
value it returned.
However, in addition to the return value, the heartbeat function also
checks the F/W result, but because no command is sent in this time
window, the result variable won't hold the expected value and we will
have a false heartbeat failure.

To avoid it, modify the "silent" skip to be done only in hard-reset.
The CPU-CP should be able to handle messages during soft-reset.

In addition to the heartbeat problem, this should also solve other
issues in other flows that send messages during soft-reset and use the
F/W result as it w/o being aware to the reset.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>