soc/intel/block/pmc: Only include the PCI driver when it is not hidden

On more recent Intel platforms FSP-S hides the PMC PCI device and the
driver is broken for those devices so don't include it at all.

Change-Id: I784be250698ec1c1e9b3b766cf1bcca55730c021
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47756
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/soc/intel/skylake/Kconfig

@@ -55,6 +55,7 @@ config CPU_SPECIFIC_OPTIONS
 	select SOC_INTEL_COMMON_BLOCK_GPIO_PADCFG_PADTOL
 	select SOC_INTEL_COMMON_BLOCK_GSPI
 	select SOC_INTEL_COMMON_BLOCK_HDA
+	select SOC_INTEL_COMMON_BLOCK_PMC_DISCOVERABLE
 	select SOC_INTEL_COMMON_BLOCK_SA
 	select SOC_INTEL_COMMON_BLOCK_SCS
 	select SOC_INTEL_COMMON_BLOCK_SGX