disp: msm: dsi: error handling during debugfs command transfer

Change clears the DSI TX command buffer allocated for debugfs
command transfers and destroys the command packets in case of
error during command transfer.

Change-Id: Ia1e822b9b60d44f7eba325116d416916419471fa
Signed-off-by: Satya Rama Aditya Pinapala <psraditya30@codeaurora.org>