drivers/elog: Fix debug build errors

Add hexdump.c to Makefile.inc and change an elog_debug format to
use %z for size_t arguments.  This corrects build errors when ELOG_DEBUG
is used.

Change-Id: I3d5547eed8ada7c4bdcbbb8bb9d6965ade73beda
Signed-off-by: John E. Kabat Jr <john.kabat@scarletltd.com>
Reviewed-on: https://review.coreboot.org/21769
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
diff --git a/src/lib/Makefile.inc b/src/lib/Makefile.inc
index 778bea8..dfb23b6 100644
--- a/src/lib/Makefile.inc
+++ b/src/lib/Makefile.inc
@@ -165,6 +165,7 @@
 ramstage-y += hexdump.c
 romstage-y += hexdump.c
 verstage-y += hexdump.c
+smm-y += hexdump.c
 
 bootblock-$(CONFIG_REG_SCRIPT) += reg_script.c
 verstage-$(CONFIG_REG_SCRIPT) += reg_script.c