soc/intel: Retype `CnviBtAudioOffload` devicetree option

The `FORCE_ENABLE` and `FORCE_DISABLE` names do not match what FSP UPDs
say, and can be confused with the `PchHdaTestPowerClockGating` UPD.

Replace the enum with a bool, and drop the confusing names. Note that
the enum for Ice Lake was incorrect, but no mainboards used the option.

Change-Id: I2c9b4c6a2f210ffca946ca196299fa672a06ccc7
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51154
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/mainboard/google/volteer/variants/baseboard/devicetree.cb b/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
index 6a826c0..825005e 100644
--- a/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
+++ b/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
@@ -289,7 +289,7 @@
 
 	register "tcc_offset" = "10"     # TCC of 90
 
-	register "CnviBtAudioOffload" = "FORCE_ENABLE"
+	register "CnviBtAudioOffload" = "true"
 
 	# Intel Common SoC Config
 	#+-------------------+---------------------------+