Add support for more than one Super I/O or EC per machine

Flashrom currently only supports exactly one Super I/O or Embedded
Controller, and this means quite a few notebooks and a small subset of
desktop/server boards cannot be handled reliably and easily.
Allow detection and initialization of up to 3 Super I/O and/or EC chips.

WARNING! If a Super I/O or EC responds on multiple ports (0x2e and
0x4e), the code will do the wrong thing (namely, initialize the hardware
twice). I have no idea if we should handle such situations, and whether
we should ignore the second chip with identical ID or not. Initializing
the hardware twice for the IT87* family is _not_ a problem, but I don't
know how well IT85* can handle it (and whether IT85* would listen at
more than one port anyway).

Corresponding to flashrom svn r1289.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>

Thanks to Thomas Schneider for testing on a board with ITE IT87* SPI.
Test report (success) is here: http://paste.flashrom.org/view.php?id=379

Thanks to David Hendricks for testing on a Google Cr-48 laptop with
ITE IT85* EC SPI. Test report (success) is here:
http://www.flashrom.org/pipermail/flashrom/2011-April/006275.html
Acked-by: David Hendricks <dhendrix@google.com>

board_enable.c

@@ -493,7 +493,6 @@ int it8705f_write_enable(uint8_t port)
 		}
 	} else {
 		msg_pdbg("No IT8705F flash segment enabled.\n");
-		/* Not sure if this is an error or not. */
 		ret = 0;
 	}
 	exit_conf_mode_ite(port);