s390/lcs: Convert sprintf to scnprintf

This LWN article explains the why scnprintf is preferred over snprintf
in general
https://lwn.net/Articles/69419/
Ie. snprintf() returns what *would* be the resulting length, while
scnprintf() returns the actual length.

Reported-by: Jules Irenge <jbi.octave@gmail.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Thorsten Winkler <twinkler@linux.ibm.com>
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/s390/net/lcs.h

@@ -21,7 +21,7 @@ do { \
 #define LCS_DBF_TEXT_(level,name,text...) \
 	do { \
 		if (debug_level_enabled(lcs_dbf_##name, level)) { \
-			sprintf(debug_buffer, text); \
+			scnprintf(debug_buffer, sizeof(debug_buffer), text); \
 			debug_text_event(lcs_dbf_##name, level, debug_buffer); \
 		} \
 	} while (0)