[ARM] S3C24XX: Fix redefine of DEFINE_TIMER() in s3c24xx pwm-clock.c

Do not redefine the DEFINE_TIMER macro. Renamed the local macro
to DEFINE_S3C_TIMER.

Signed-off-by: Nelson Castillo <nelsoneci@gmail.com>
[ben-linux@fluff.org: spelling and subject fix]
Signed-off-by: Ben Dooks <ben-linux@fluff.org>