Add Intel Gigabit NIC SPI flashing support

Tested on a 82541PI (0x8086, 0x107c) using 32-bit hardware.

The last line in nicintel_request_spibus() could be changed so that FL_BUSY
is used instead.

Shortened sample log:
[...]
Found "Intel 82541PI Gigabit Ethernet Controller" (8086:107c, BDF 01:03.0).
Found chip "ST M25P10.RES" (128 KB, SPI) at physical address 0xfffe0000.
Multiple flash chips were detected: M25P05.RES M25P10.RES
Please specify which chip to use with the -c <chipname> option.
[...]

Corresponding to flashrom svn r1151.

Signed-off-by: Idwer Vollering <vidwer@gmail.com>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>
diff --git a/flashrom.8 b/flashrom.8
index 8e7c02b..47312a0 100644
--- a/flashrom.8
+++ b/flashrom.8
@@ -190,6 +190,9 @@
 .BR "* rayer_spi" " (for SPI flash ROMs attached to a RayeR parport \
 based programmer)"
 .sp
+.BR "* nicintel_spi" " (for SPI flash ROMs attached to an Intel Gigabit \
+network cards)"
+.sp
 Some programmers have optional or mandatory parameters which are described
 in detail in the
 .B PROGRAMMER SPECIFIC INFO