3 uapi header files(mxc_sim_interface.h, pxp_dma.h, pxp_device.h) cannot be installed by the command "make headers_install" because they are not in Kbuild list, which impacts the linux-test build. This patch adds the 3 header files in Kbuild list. Signed-off-by: Gao Pan <B54642@freescale.com>