Introduce enable_flash_ich_fwh_decode().

ICH2 (and C-ICH)/3/4/5 also have FWH_SEL1/2 registers but at
different addresses. In preparation for implementing fwh_idsel
parsing for older ICH chipsets extract the parameter handling
and add variables for the offsets.

While FWH_DEC_EN1 is a 16bit register for ICH6, it is two separate
8bit registers on ICH5 and earlier. Implement all accesses with two
byte instructions instead, to prepare for extended support.

Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Acked-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>

git-svn-id: svn://flashrom.org/flashrom/trunk@1746 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1
Use ich_generation parameter in enable functions prior to ICH7.

Follow the style used from ICH7 onwards to pass ich_generation
parameter to lower-level functions on older ICH chipsets too.

Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Signed-off-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>

git-svn-id: svn://flashrom.org/flashrom/trunk@1747 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1
Enable fwh_idsel parameter for C-ICH and ICH2/3/4/5 chipsets.

Register locations are different from ICH6, but otherwise appear
to have identical bit specifications and defaults.

Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Acked-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>

git-svn-id: svn://flashrom.org/flashrom/trunk@1748 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1