moved examples/imageon/i2chdmi.h to lib/cpp and removed gralloc/i2chdmi.h

Change-Id: I8d2e1fbaa4920aba40eb7352a59312d58a4f5ac8
added call to init_i2c_hdmi() to testhdmidisplay.cpp

Change-Id: Ie297cd9cb5eaf4bc1643e3f50153f041162a1916
added rule to build examples/hdmidisplay to  gralloc Makefile

Change-Id: Ib579e8db6d4b5b11ec527b527285396ec9fb4b30