msm: vidc: add slice info extradata feature for encoder

One frame can have multiple slices or NAL units in the
encoded bitstream output. Core can give slices information
to the driver, if slice info metadata enabled, which inturn
will be sent to the client as extradata in output buffer.
This change will enable the core with slice information
extradata feature.

Change-Id: I52935a641dc7b4921da602b0132f0b81463b5cc8
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>