rpmsg: glink: Initialize the "intent_req_comp" completion variable

The "intent_req_comp" variable is used without initialization which
results in NULL pointer dereference in qcom_glink_request_intent().

we need to initialize the completion variable before using it.

Fixes: 27b9c5b6

 ("rpmsg: glink: Request for intents when unavailable")
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>