msm_fb: Clear real pipe attributes in the pipe free

Clear original pipe attributes in the pipe free call.

Change-Id: I776869e7997e5b70e4c2b102e1a394034247bbcd
Signed-off-by: Kalyan Thota <kalyant@codeaurora.org>
Signed-off-by: Naseer Ahmed <naseer@codeaurora.org>