soc/intel/skylake: Control fixed IO decode from devicetree

The current implementation doesn't allow custom values for the LPC IO
decodes and IO enables.

Add the lpc_ioe and lpc_iod values. If they are not zero, they will be
used instead of the current handling for COMA and COMB.

BUG=N/A
TEST=tested on facebook monolith

Change-Id: Iad7bb0e44739e8d656a542c79af7f98a4e9bde69
Signed-off-by: Wim Vervoorn <wvervoorn@eltan.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38748
Reviewed-by: Frans Hendriks <fhendriks@eltan.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/skylake/chip.h

@@ -79,6 +79,10 @@ struct soc_intel_skylake_config {
 	uint8_t gpe0_dw1; /* GPE0_63_32 STS/EN */
 	uint8_t gpe0_dw2; /* GPE0_95_64 STS/EN */
 
+	/* LPC fixed enables and ranges */
+	uint16_t lpc_iod;
+	uint16_t lpc_ioe;
+
 	/* Generic IO decode ranges */
 	uint32_t gen1_dec;
 	uint32_t gen2_dec;