add t440p/w541 configs using broadwell mrc
    
    broadwell mrc enables both igpu and dgpu to be enabled
    at any given time. if the onboard (intel) gpu is set as
    primary, the logic to disable it is not executed within
    coreboot; instead, the igpu is used for vga decode.
    
    on some t440p/w541 thinkpads, both an intel and nvidia
    gpu are present. in this setup, the intel gpu must be
    used for vga, and all output, but rendering can be
    offloaded to the nvidia gpu (nvidia optimus).
    
    optimus would never work on haswell mrc.bin, because it
    always disables the igpu when a dgpu is present, so a hack
    exists in coreboot that hides the dgpu from mrc, so that the
    igpu remains enabled. broadwell mrc doesn't do this, so the
    option to hide PEG devices has been disabled in these
    configs.
    
    the broadwell mrc has better peg device handling, and can
    support 16gb modules on broadwell hardware; it may well
    support these modules on haswell hardware too, though ddr3
    sodimms are very hard to find (and expensive). (and currently
    untested, with this patch)
    
    Signed-off-by: Leah Rowe <leah@libreboot.org>