[SPARC]: Provide generic ioctls in Sparc RTC driver.

Provide support for drivers/char/rtc.c ioctls in the
Mostek rtc driver as well as the Sparc specific RTCGET
and RTCSET.

This allows userspace to be much less messy.  Currently
util-linux and other spots jump through hoops trying
various ioctl variants until it hits the right one whatever
driver actually being used supports.

Eventually all of this should move over to the genrtc.c
driver, but not today...

While we are here, fix up the register types for sparse.

Thanks to Frans Pop for helping point out this issue.

Signed-off-by: David S. Miller <davem@davemloft.net>