pstore: Improve and update some comments and status output

This improves and updates some comments:
 - dump handler comment out of sync from calling convention
 - fix kern-doc typo

and improves status output:
 - reminder that only kernel crash dumps are compressed
 - do not be silent about ECC infrastructure failures

Signed-off-by: Kees Cook <keescook@chromium.org>

fs/pstore/platform.c

@@ -304,7 +304,7 @@ static void allocate_buf_for_compression(void)
 	big_oops_buf_sz = size;
 	big_oops_buf = buf;
 
-	pr_info("Using compression: %s\n", zbackend->name);
+	pr_info("Using crash dump compression: %s\n", zbackend->name);
 }
 
 static void free_buf_for_compression(void)
@@ -354,9 +354,8 @@ void pstore_record_init(struct pstore_record *record,
 }
 
 /*
- * callback from kmsg_dump. (s2,l2) has the most recently
- * written bytes, older bytes are in (s1,l1). Save as much
- * as we can from the end of the buffer.
+ * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
+ * end of the buffer.
  */
 static void pstore_dump(struct kmsg_dumper *dumper,
 			enum kmsg_dump_reason reason)