msm: smd_pkt: Extend write operation to send data larger than SMD FIFO

The SMD_PKT driver write operation restricts the maximum data size to
the corresponding SMD channel size. The user-space application wants
to send more data than the SMD channel size. So update the write operation
to send data larger than SMD channel size.

Change-Id: Icf4b62ceaaca9305188d3a6d78a44d1c48aadca8
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>