soc: qcom: glink: Fix tx_ready cleanup list during ssr

The tx_ready list is not cleaned up as a part of ssr. As a result,
glink core still tries to send packets that are in flight leading
to unnecessary error logs. The device may crash because of it.

Cleanup the tx_ready list in ssr before notifying the transport
about ssr.

CRs-Fixed: 862574
Change-Id: I3cc340d07a828e354bec3cc3b1ecbe4630334799
Signed-off-by: Atish Kumar Patra <apatra@codeaurora.org>