copybit: Initialize release & acquire fence fds of Copybit context.

Initialize release and acquire fence fds of Copybit context to -1.
Otherwise fd 0 gets closed in first call to msm_copybit, which is
valid fd and it leads to bad state if fd 0 is being used as stdin.

Change-Id: I01278bbb580d61e2d4b4c7b3f7b346274af6d914
1 file changed