cbmem: Fix cbmem_add_bootmem()

Change 13363 (555d6c2) introduced a bug where cbmem_add_bootmem() was
converted to use a new function. Unfortunately instead of passing a
pointer, NULL was passed due to type confusion. This change fixes that
problem by passing address of stack variable instead of NULL.

Change-Id: Ib8e1add3547cda01f71bf1dea14d3e58bdd99730
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://review.coreboot.org/14033
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
diff --git a/src/lib/imd_cbmem.c b/src/lib/imd_cbmem.c
index e75c538..a078071 100644
--- a/src/lib/imd_cbmem.c
+++ b/src/lib/imd_cbmem.c
@@ -272,11 +272,11 @@
 
 void cbmem_add_bootmem(void)
 {
-	void *base = NULL;
+	uintptr_t base = 0;
 	size_t size = 0;
 
-	cbmem_region_used(base, &size);
-	bootmem_add_range((uintptr_t)base, size, LB_MEM_TABLE);
+	cbmem_region_used(&base, &size);
+	bootmem_add_range(base, size, LB_MEM_TABLE);
 }
 
 #if ENV_RAMSTAGE