soc/intel/apollolake: Add PCIe de-emphasis enable configuration.

PCIe de-emphasis is enabled by default. Thunderpeak Wi-Fi requires
it to be disabled. Therefore allow it to be configured via a
device tree setting.

TEST=On GLKRVP, verify Thunderpeak Wi-Fi card shows up in lspci when
de-emphasis is disabled in device tree.

Change-Id: Iae204768dfe00a638c764644c44c7cda269e73e0
Signed-off-by: Shamile Khan <shamile.khan@intel.com>
Reviewed-on: https://review.coreboot.org/25185
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2 files changed