x86, mce: use extended sysattrs for the check_interval attribute.

Instead of using own callbacks use the generic ones provided by
the sysdev later.

This finally allows to get rid of the ugly ACCESSOR macros. Should
also save some text size.

[ Impact: cleanup ]

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>