rpmsg: qcom: correct kerneldoc

Correct kerneldoc warnings like:

  drivers/rpmsg/qcom_glink_ssr.c:45:
    warning: expecting prototype for G(). Prototype was for GLINK_SSR_DO_CLEANUP() instead

Also fix meaning of 'flag' argument.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220519073330.7187-3-krzysztof.kozlowski@linaro.org