amd/stoneyridge: Clarify SPD structure in chip.h

Add #define values and clarify the spdAddrLookup array.

Change-Id: I39b9913a2fd52f9105e4a771f651a8d9649202e6
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/21852
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/stoneyridge/chip.h

@@ -18,8 +18,12 @@
 
 #include <stdint.h>
 
+#define MAX_NODES 1
+#define MAX_DRAM_CH 1
+#define MAX_DIMMS_PER_CH 2
+
 struct soc_amd_stoneyridge_config {
-	u8 spdAddrLookup[1][1][2];
+	u8 spdAddrLookup[MAX_NODES][MAX_DRAM_CH][MAX_DIMMS_PER_CH];
 };
 
 typedef struct soc_amd_stoneyridge_config config_t;