Several hardware features of SGI's IOC4 I/O controller chip require
timing-related driver calculations dependent upon the PCI bus speed.  This
patch enables the core IOC4 driver code to detect the actual bus speed and
store a value that can later be used by the IOC4 subdrivers as needed.

Signed-off-by: Brent Casavant <bcasavan@sgi.com>
Acked-by: Pat Gefre <pfg@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>