[ARM] S3C24A0: Remove duplicate <mach/io.h> file

The commit 39263db7986bf15c753f6847699107bdf5a2e318 added
a default <mach/io.h> implementation which is shared if
needed between all the s3c implementations. Remove the
s3c24a0 version which is the same as this.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>