drivers/sensors: s5j/ppd42ns: modify ppd42ns dust sensor driver

drivers/sensors: s5j/ppd42ns: modify ppd42ns dust sensor driver

This patch modifies ppd42ns driver according to Tizen RT device driver
model. The previous ppd42ns driver has implemented according to common
sensor API definition (os/include/tinyara/sensors/sensor.h). The common
sensor API will be removed.

The details are as follows.

 1. remove common sensor API definition
      : os/include/tinyara/sensors/sensor.h
 2. modify ppd42ns driver according to Tizen RT device driver model
    - implement open, close and read operations
    - implement board dependent functions as callback
    - implement the function for registering character driver
      : os/drivers/sensors/ppd42ns.c
        os/include/tinyara/sensors/ppd42ns.h
 3. add Samsung S5JT200 code for implementing board dependent callback
      : os/arch/arm/src/s5j/s5j_ppd42ns.c
        os/arch/arm/src/s5j/s5j_ppd42ns.h
 4. add sensor driver registering code on board initialization
      : os/arch/arm/src/artik053/src/artik053_boot.c,
        os/arch/arm/src/sidk_s5jt200/src/s5jt200_boot.c
 5. modify ppd42ns example application using file operation
      : apps/examples/sensor_test/ppd42ns_test.c

Change-Id: I14ae5e10a3624cf8bb7125137323fcc3bb6c50ca
Signed-off-by: Wonsang Ryou <wonsang.yoo@samsung.com>