[coreboot] ThinkPad X201 compile error

[Federico Amedeo Izzo]

Hello,

I wanted to update coreboot on my X201 from the Feb 2017 source
(commit 068edc1c52cb1e5b6376ba7f296ef8797a24cd5f)
to current master
(commit f2e7b37c52cac5e7825d0e01b3c45c1506e99253)
But when compiling it gives the following error
```
src/northbridge/intel/nehalem/gma.c: In function 'gma_func0_init':
src/northbridge/intel/nehalem/gma.c:1066:5: error: implicit declaration
of function 'intel_gma_init' [-Werror=implicit-function-declaration]
     intel_gma_init(conf, res2mmio(gtt_res, 0, 0),```

Now it's configured to load a VGA blob, if I enable "native graphics
init" instead, the compile error goes away, but the resulting image does
not boot (beep and flashing leds)

I attached the configuration that gives the compilation error.

Do you have any suggestions?

Thanks,

Federico