msm: qdss: switch to using qdss apis in the etm driver

ETM driver is a qdss source and currently directly calls the etb,
funnel and tpiu apis causing tight coupling between the drivers.
Instead switch to using the new external apis (qdss_get/put,
qdss_enable/disable) provided by the qdss driver.

Qdss apis will be used by other qdss sources as well and going
through the qdss driver apis will decouple the etm source driver
from the link (funnel) and sink (etb, tpiu) drivers that are part
of the qdss block.

Change-Id: I0dc64d88aa9647787946ba1d4e351231a74a3cf9
Signed-off-by: Pratik Patel <pratikp@codeaurora.org>