soc: qcom: glink: fix race condition while getting rx fifo during ssr

When system goes up driver is trying to allocate rx_fifo from
ssr thread and interrupt handler as well, which can result in
race condition.

Taking spin lock before allocating rx_fifo to avoid race condition.

CRs-Fixed: 2502912
Change-Id: Ibe7b345d4e4edb7e837b84ddd4c03c3873ccf033
Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org>