soc: qcom: glink_spi_xprt: Add support for WDSP SSR

Handle WDSP_EVENT_PRE_SHUTDOWN event to indicate link down event to G-Link
core and the clients of G-Link. Handle WDSP_EVENT_POST_BOOTUP event to
indicate link up event.

CRs-Fixed: 1080354
Change-Id: I12c04ceb7af51cc5d2f0c79b524ef783dc5f749e
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>