device/dram/ddr2: Add common ddr2 spd decoder

Decode DDR2 SPD similar to DDR3 SPD decoder to ease
readability, reduce code complexity and reduce size of
maintainable code.

Rename dimm_is_registered to spd_dimm_is_registered_ddr3 to avoid
compilation errors.

Change-Id: I741f0e61ab23e3999ae9e31f57228ba034c2509e
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/18273
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins)
diff --git a/src/include/device/dram/ddr3.h b/src/include/device/dram/ddr3.h
index ee20ba7..7a97bf8 100644
--- a/src/include/device/dram/ddr3.h
+++ b/src/include/device/dram/ddr3.h
@@ -201,7 +201,7 @@
 u16 spd_ddr3_calc_crc(u8 *spd, int len);
 u16 spd_ddr3_calc_unique_crc(u8 *spd, int len);
 int spd_decode_ddr3(dimm_attr * dimm, spd_raw_data spd_data);
-int dimm_is_registered(enum spd_dimm_type type);
+int spd_dimm_is_registered_ddr3(enum spd_dimm_type type);
 void dram_print_spd_ddr3(const dimm_attr * dimm);
 int spd_xmp_decode_ddr3(dimm_attr * dimm,
 			spd_raw_data spd,