soc: qcom: glink: Make ch_get_dummy_rx_intent() atomic

Transports may end up invoking ch_get_dummy_rx_intent() in atomic context,
which will lead to a sleeping while atomic warning due to a GFP_KERNEL
allocation.  Change the allocation to GFP_ATOMIC to silence the warning.

Change-Id: If3f94ec0eb8d42f37713e084ddfc2aa9e81fe978
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>