nami: Undef CONFIG_USBC_SS_MUX_DFP_ONLY to enable device mode
nami: Undef CONFIG_USBC_SS_MUX_DFP_ONLY to enable device mode

In order to enable device mode on nami, we need to remove the
CONFIG_USBC_SS_MUX_DFP_ONLY option.  This will allow for the type C
port to become an up facing port, which is needed for adb.

BUG=b:110443736
BRANCH=Nami
TEST=Ensure when attached to workstation, adb devices shows
     nami device and adb debugging popup appears in nami device.

Change-Id: Icaec13af4246262931c19beb7e64bae41e721d96
Signed-off-by: Shelley Chen <ab7b8cc85923339aed379eb1c5cc4dccfd2eb3d7@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1142226
Commit-Ready: ChromeOS CL Exonerator Bot <fa429e5907f00867f797423aea74327bb02c91b6@appspot.gserviceaccount.com>
Tested-by: Shelley Chen <ab7b8cc85923339aed379eb1c5cc4dccfd2eb3d7@chromium.org>
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>
Reviewed-by: Furquan Shaikh <6be5c96c464778f89679b1062a2e0a6af93d2aa5@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec