[coreboot-gerrit] Change in coreboot[master]: mb/google/volteer: Configure GPP_A19 and GPP_A20 as PAD_NC

[Wonkyu Kim (Code Review)]

Wonkyu Kim has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/44501 )

Change subject: mb/google/volteer: Configure GPP_A19 and GPP_A20 as PAD_NC
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Patch Set 2:

Native function pin mux for DPs are done by FSP after pin mux by gpio.c
So, we also need to configure below in overridetree.cb for not confuring DP_HPD1 and DP_HPD2.
register "DdiPort1Hpd" = "0"
register "DdiPort2Hpd" = "0"
Note that these are enabled in devicetree.cb in baseboard.