debug: coredump: remove z_ prefix for stuff used outside subsys

This removes the z_ prefix those (functions, enums, etc.) that
are being used outside the coredump subsys. This aligns better
with the naming convention.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>

kernel/fatal.c

diff --git a/kernel/fatal.c b/kernel/fatal.c
index a31e0f1..e73608a 100644
--- a/kernel/fatal.c
+++ b/kernel/fatal.c
@@ -121,7 +121,7 @@
 	LOG_ERR("Current thread: %p (%s)", thread,
 		log_strdup(thread_name_get(thread)));
 
-	z_coredump(reason, esf, thread);
+	coredump(reason, esf, thread);
 
 	k_sys_fatal_error_handler(reason, esf);