ARM: s3c24xx: include common.h header in s3c2443.c

Include common.h header in the s3c2443.c to bring the prototypes of
defined functions and fix W=1 compile warnings:

    arch/arm/mach-s3c24xx/s3c2443.c:60:12: warning: no previous prototype for 's3c2443_init' [-Wmissing-prototypes]
    arch/arm/mach-s3c24xx/s3c2443.c:77:13: warning: no previous prototype for 's3c2443_init_uarts' [-Wmissing-prototypes]
    arch/arm/mach-s3c24xx/s3c2443.c:88:13: warning: no previous prototype for 's3c2443_map_io' [-Wmissing-prototypes]

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