Set max_mem_clock_mhz in devicetree to 933Mhz. Allows to run the memory at up to DDR3-1866. The same frequency was allowed within the first vendor bios, but Lenovo than decided to limit it to DDR3-1333. Tested on Lenovo T520 and DDR3-1600 DIMM (RMT3170eb86e9w16). The RAM is now running at DDR3-1600 instead of DDR3-1333. This gives about 4% performance increase in glmark2 using the Intel GPU. Change-Id: If15be497402d84a2778f0434b6381a64eda832d6 Signed-off-by: Patrick Rudolph <siro@das-labor.org> Reviewed-on: https://review.coreboot.org/15158 Tested-by: build bot (Jenkins) Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Martin Roth <martinroth@google.com>