AMD Northbridge LX: convert spd_read_byte() to non-static version

Change-Id: Ie329606852dfd7109acb694e9a9ff851b023cc63
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-on: http://review.coreboot.org/3369
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
18 files changed