Squashed commit of the following:
configs: Each board now initializes the touchscreen controller as a normal part of its board bring-up. board_tsc_setup() is gone; the touchscreen controller is now treated like any other on-board device.
Remove all support for BOARDIOC_TSCTEST_SETUP
Move prototype for board_tsc_setup() from include/nuttx/board.h to individual board header files.