x86: ich6-gpio: Add Intel Tunnel Creek GPIO support

x86: ich6-gpio: Add Intel Tunnel Creek GPIO support

Intel Tunnel Creek GPIO register block is compatible with current
ich6-gpio driver, except the offset and content of GPIO block base
address register in the LPC PCI configuration space are different.

Use u16 instead of u32 to store the 16-bit I/O address of the GPIO
registers so that it could support both Ivybridge and Tunnel Creek.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>