mb/google/nissa: Enable Cnvi BT Audio Offload feature

This patch enables Cnvi BT Audio Offload feature and also
configures the virtual GPIO for CNVi Bluetooth I2S pads.

BUG=b:233834597
TEST=Verified BT offload feature on Nivviks P1.

Signed-off-by: V Sowmya <v.sowmya@intel.com>
Change-Id: Iffbd08351d083d2b550f309994af931bceb257d9
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65670
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Reviewed-by: Krishna P Bhat D <krishna.p.bhat.d@intel.com>
Reviewed-by: Sridhar Siricilla <sridhar.siricilla@intel.com>
Reviewed-by: Reka Norman <rekanorman@chromium.org>
diff --git a/src/mainboard/google/brya/variants/nivviks/overridetree.cb b/src/mainboard/google/brya/variants/nivviks/overridetree.cb
index 38b6569..6e6806a 100644
--- a/src/mainboard/google/brya/variants/nivviks/overridetree.cb
+++ b/src/mainboard/google/brya/variants/nivviks/overridetree.cb
@@ -50,6 +50,9 @@
 		.vnn_icc_max_ma = 500,
 	}"
 
+	# Enable the Cnvi BT Audio Offload
+	register "cnvi_bt_audio_offload" = "1"
+
 	# Intel Common SoC Config
 	#+-------------------+---------------------------+
 	#| Field             |  Value                    |