trace: rename trace_print_hex_seq arg and add kdoc

Steven suggested to improve trace_print_hex_seq() a bit after commit
2acae0d5b0f7 ("trace: add variant without spacing in trace_print_hex_seq")
in two ways: i) by adding a kdoc comment for the helper function
itself and ii) by renaming 'spacing' argument into 'concatenate'
to better denote that we don't add spaces between each hex bytes.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h
index 9f68462..5c06f4a 100644
--- a/include/trace/trace_events.h
+++ b/include/trace/trace_events.h
@@ -298,11 +298,11 @@
 
 #undef __print_hex
 #define __print_hex(buf, buf_len)					\
-	trace_print_hex_seq(p, buf, buf_len, true)
+	trace_print_hex_seq(p, buf, buf_len, false)
 
 #undef __print_hex_str
 #define __print_hex_str(buf, buf_len)					\
-	trace_print_hex_seq(p, buf, buf_len, false)
+	trace_print_hex_seq(p, buf, buf_len, true)
 
 #undef __print_array
 #define __print_array(array, count, el_size)				\