nb/intel/haswell/raminit: Die if cbmem_add() fails

Maybe we could go on, but cbmem_add() failing is a very bad sign.
Should fix coverity CID 1376384 (Null pointer dereferences
(NULL_RETURNS)).

Change-Id: I330cee6db3540c6a9c408d56da43105de5d075f7
Found-by: Coverity Scan #1376384
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/20280
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
diff --git a/src/northbridge/intel/haswell/raminit.c b/src/northbridge/intel/haswell/raminit.c
index 50443aa..aa07f16 100644
--- a/src/northbridge/intel/haswell/raminit.c
+++ b/src/northbridge/intel/haswell/raminit.c
@@ -187,6 +187,8 @@
 	int dimm_cnt = 0;
 
 	mem_info = cbmem_add(CBMEM_ID_MEMINFO, sizeof(struct memory_info));
+	if (!mem_info)
+		die("Failed to add memory info to CBMEM.\n");
 	memset(mem_info, 0, sizeof(struct memory_info));
 
 	addr_decoder_common = MCHBAR32(0x5000);