[PATCH] Fixes and tweaks for sis(4)

[John Baldwin]

Patch below does the following:
- Remove sis_unit using if_printf() and device_printf() instead.
- Use callout_init_mtx() for the callout.
- Remove spls.
- Fix locking for the ifmedia to happen in the ifmedia handlers
  rather than in sis_ioctl().

Please test.  Thanks!

http://www.FreeBSD.org/~jhb/patches/sis_locking.patch

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org