device/Kconfig: Fix selection of software connection manager

The patch that introduced the selection of software connection manager,
CB:64561 - 060df17f1d (soc/intel/alderlake/acpi: Add Kconfig options for
SCM and FCM) added a default to enable the software configuration
manager directly in the choice.

This leads to warnings when running make menuconfig:
src/soc/intel/alderlake/Kconfig:439:
warning: defaults for choice values not supported
src/soc/intel/meteorlake/Kconfig:337:
warning: defaults for choice values not supported
src/soc/intel/tigerlake/Kconfig:299:
warning: defaults for choice values not supported

I'm not sure why the Kconfig linter didn't catch this, but this
issue is currently breaking the build for me.  This patch fixes
it so that instead of setting the default directly, a new Kconfig
value is selected that then sets the default correctly.

Signed-off-by: Martin Roth <gaumless@gmail.com>
Change-Id: I674046a93af8f7c2f3003900804deefa89dae295
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71776
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Sean Rhodes <sean@starlabs.systems>
diff --git a/src/soc/intel/alderlake/Kconfig b/src/soc/intel/alderlake/Kconfig
index a5332b0..d4c4be8 100644
--- a/src/soc/intel/alderlake/Kconfig
+++ b/src/soc/intel/alderlake/Kconfig
@@ -435,8 +435,8 @@
 	help
 	  Enables ACPI entry to provide silicon type information to IPU kernel driver.
 
-config SOFTWARE_CONNECTION_MANAGER
-	default y if CHROMEOS
+config CHROMEOS
+	select DEFAULT_SOFTWARE_CONNECTION_MANAGER
 
 config ALDERLAKE_ENABLE_SOC_WORKAROUND
 	bool