Add Gigadevice SPI rom support

Add support for GigaDevice SPI ROMS.
The GD25Q64B device has been tested, the other rom devices added to the
file have not.

Change-Id: If35676ca6b90329f15667ebb32efa0d1a159ae91
Signed-off-by: Martin Roth <martin@se-eng.com>
Reviewed-on: http://review.coreboot.org/1747
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
5 files changed