platform/x86: DELL_WMI use depends on instead of select for DELL_SMBIOS

If DELL_WMI "select"s DELL_SMBIOS, the DELL_SMBIOS dependencies are
ignored and it is still possible to end up with unmet direct
dependencies.

Change the select to a depends on.
Tested-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

drivers/platform/x86/Kconfig

@@ -168,8 +168,8 @@ config DELL_WMI
 	depends on DMI
 	depends on INPUT
 	depends on ACPI_VIDEO || ACPI_VIDEO = n
+	depends on DELL_SMBIOS
 	select DELL_WMI_DESCRIPTOR
-	select DELL_SMBIOS
 	select INPUT_SPARSEKMAP
 	---help---
 	  Say Y here if you want to support WMI-based hotkeys on Dell laptops.