rpmsg: smd: fix kerneldoc warnings

This patch fixes below kerneldoc warnings

qcom_smd.c:141: warning: Function parameter or member 'dev' not described in 'qcom_smd_edge'
qcom_smd.c:141: warning: Function parameter or member 'name' not described in 'qcom_smd_edge'
qcom_smd.c:141: warning: Function parameter or member 'new_channel_event' not described in 'qcom_smd_edge'
qcom_smd.c:222: warning: Function parameter or member 'qsept' not described in 'qcom_smd_channel'
qcom_smd.c:222: warning: Function parameter or member 'registered' not described in 'qcom_smd_channel'
qcom_smd.c:222: warning: Function parameter or member 'state_change_event' not described in 'qcom_smd_channel'
qcom_smd.c:222: warning: Function parameter or member 'drvdata' not described in 'qcom_smd_channel'
qcom_smd.c:737: warning: Function parameter or member 'wait' not described in '__qcom_smd_send'

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>