spd_cache debug: Log invalid CRC checksum

"SPD has a invalid or zero-valued CRC" is not a very useful message,
so show the actual and expected values.

Change-Id: I31a1cdacc82240c699627769d490b94f5d378e86
Signed-off-by: Tobias Diedrich <ranma+coreboot@tdiedrich.de>
Reviewed-on: http://review.coreboot.org/7393
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/src/device/dram/spd_cache.c b/src/device/dram/spd_cache.c
index 0032f32..7ecd1dc 100644
--- a/src/device/dram/spd_cache.c
+++ b/src/device/dram/spd_cache.c
@@ -52,7 +52,8 @@
 	if (((buf[SPD_CRC_LO] == 0) && (buf[SPD_CRC_HI] == 0))
 	 || (buf[SPD_CRC_LO] != (crc & 0xff))
 	 || (buf[SPD_CRC_HI] != (crc >> 8))) {
-		printk(BIOS_WARNING, "SPD has a invalid or zero-valued CRC\n");
+		printk(BIOS_WARNING, "SPD CRC %02x%02x is invalid, should be %04x\n",
+			buf[SPD_CRC_HI], buf[SPD_CRC_LO], crc);
 		buf[SPD_CRC_LO] = crc & 0xff;
 		buf[SPD_CRC_HI] = crc >> 8;
 		u16 i;