msm: ipa: fix to validate the ioctl WAN_IOC_SEND_LAN_CLIENT_MSG params

When processing WAN_IOC_SEND_LAN_CLIENT_MSG ioctl there is a possibility
of message_type being invalid and this can lead to out of buffer error.
Make a change to validate the ioctl params before processing.

Change-Id: If7955f77863b772ae1c8feda5ca0145c822403b9
Signed-off-by: Chaitanya Pratapa <cpratapa@codeaurora.org>