platform/x86: dell-smbios: Resolve dependency error on DCDBAS

When the DELL_SMBIOS_SMM backend is enabled, the DELL_SMBIOS symbol
depends on DELL_DCDBAS, and we must avoid the situation where
DELL_SMBIOS=y and DCDBAS=m.

Adding the conditional dependency to DELL_SMBIOS such as:

depends !DELL_SMBIOS_SMM || (DCDBAS || DCDBAS=n)

results in the Kconfig tooling complaining about a circular dependency,
although it appears to work in practice.

Avoid the errors by simplifying the dependency and forcing DELL_SMBIOS
to be <= DCDBAS if DCDBAS is enabled (thanks to Greg KH for the
suggestion).

Cc: Mario.Limonciello@dell.com
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

drivers/platform/x86/Kconfig

@@ -105,8 +105,14 @@ config ASUS_LAPTOP
 
 	  If you have an ACPI-compatible ASUS laptop, say Y or M here.
 
+#
+# If the DELL_SMBIOS_SMM feature is enabled, the DELL_SMBIOS driver
+# becomes dependent on the DCDBAS driver. The "depends" line prevents a
+# configuration where DELL_SMBIOS=y while DCDBAS=m.
+#
 config DELL_SMBIOS
 	tristate "Dell SMBIOS driver"
+	depends on DCDBAS || DCDBAS=n
 	---help---
 	This provides support for the Dell SMBIOS calling interface.
 	If you have a Dell computer you should enable this option.