ARM: s3c24xx: ts: include platform data header

Include platform_data/touchscreen-s3c2410.h header in the touchscreen
code to bring the prototypes of defined functions and fix W=1 compile
warning:

    arch/arm/mach-s3c24xx/setup-ts.c:24:6: warning: no previous prototype for 's3c24xx_ts_cfg_gpio' [-Wmissing-prototypes]

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>