slimbus: qcom-ngd-ctrl: Avoid sending power requests without QMI

slimbus: qcom-ngd-ctrl: Avoid sending power requests without QMI

Attempting to send a power request during PM operations, when the QMI
handle isn't initialized results in a NULL pointer dereference. So check
if the QMI handle has been initialized before attempting to post the
power requests.

Fixes: 917809e2280b ("slimbus: ngd: Add qcom SLIMBus NGD driver")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20201127102451.17114-7-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>