msm: qmi: Correct the maximum message length calculation

Maximum message length calculation is incorrect under array of structures
scenario.

Multiply the size of each structure with the maximum array length while
calculating the maximum message length.

Change-Id: I8272b1b17ce303cd453807d39cbf110766a7ed31
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>