spi_s3c24xx: use dev_pm_ops

Change the spi_s3c24xx driver to use dev_pm_ops to avoid the following
warning during probe:

Platform driver 's3c2410-spi' needs updating - please use dev_pm_ops

Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>