Reuse latest pipeline if possible

Reuse latest pipeline if possible

Search pipeline cache is quite heay operation.
So if we can re-use pipeline, It will be helpful
if we use equal shader continously.

It will give power for 3D layer who did depth test, so
rendering order is determined by shader, texture and geometry.

Change-Id: I3bf9abab125b6adebad5ecc6bb04463d7e3db972
Signed-off-by: Eunki Hong <eunkiki.hong@samsung.com>