mb/google/auron: Drop spd.h from variants

Factor out common DRAM SPD definitions and relocate SPD GPIO macros.
Also factor out common function definition. Drop now-empty headers.

Change-Id: Id05ba6c9cea27fbad5ee831f033d0de43717847e
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49770
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>

src/mainboard/google/auron/variant.h

@@ -11,4 +11,18 @@ int variant_smbios_data(struct device *dev, int *handle,
 void variant_romstage_entry(struct romstage_params *rp);
 void lan_init(void);
 
+void mainboard_fill_spd_data(struct pei_data *pei_data);
+
+#define SPD_LEN			256
+
+#define SPD_DRAM_TYPE		2
+#define SPD_DRAM_DDR3		0x0b
+#define SPD_DRAM_LPDDR3		0xf1
+#define SPD_DENSITY_BANKS	4
+#define SPD_ADDRESSING		5
+#define SPD_ORGANIZATION	7
+#define SPD_BUS_DEV_WIDTH	8
+#define SPD_PART_OFF		128
+#define SPD_PART_LEN		18
+
 #endif