[ARM] Add comments marking in-use ptrace numbers

Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

include/asm-arm/ptrace.h

@@ -10,23 +10,19 @@
 #ifndef __ASM_ARM_PTRACE_H
 #define __ASM_ARM_PTRACE_H
 
-
 #define PTRACE_GETREGS		12
 #define PTRACE_SETREGS		13
 #define PTRACE_GETFPREGS	14
 #define PTRACE_SETFPREGS	15
-
+/* PTRACE_ATTACH is 16 */
+/* PTRACE_DETACH is 17 */
 #define PTRACE_GETWMMXREGS	18
 #define PTRACE_SETWMMXREGS	19
-
+/* 20 is unused */
 #define PTRACE_OLDSETOPTIONS	21
-
 #define PTRACE_GET_THREAD_AREA	22
-
 #define PTRACE_SET_SYSCALL	23
-
 /* PTRACE_SYSCALL is 24 */
-
 #define PTRACE_GETCRUNCHREGS	25
 #define PTRACE_SETCRUNCHREGS	26