flashrom.8.tmpl: Clarify supported ft2232_spi frequencies

The manpage suggests that ft2232_spi chips are only capable of up to
6 MHz SPI clock frequencies, whereas flashrom disables the divide-by-5
prescaler on the 'H' chips allowing up to 30 MHz frequencies. This
detail was already present in the comments of ft2232_spi.c.

Signed-off-by: Nicholas Chin <nic.c3.14@gmail.com>
Change-Id: Id7690e1d4e11a3d0495afbc650f3c67430946468
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/70218
Original-Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Original-Reviewed-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72366
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/flashrom.8.tmpl b/flashrom.8.tmpl
index 7cb0c42..402fa5d 100644
--- a/flashrom.8.tmpl
+++ b/flashrom.8.tmpl
@@ -828,8 +828,8 @@
 expressible divisors are all
 .B even
 numbers between 2 and 2^17 (=131072) resulting in SPI clock frequencies of
-6 MHz down to about 92 Hz for 12 MHz inputs. The default divisor is set to 2, but you can use another one by
-specifying the optional
+6 MHz down to about 92 Hz for 12 MHz inputs (non-H chips) and 30 MHz down to about 458 Hz for 60 MHz inputs ('H' chips). The default
+divisor is set to 2, but you can use another one by specifying the optional
 .B divisor
 parameter with the
 .sp