missing user_stack_pointer() instances

for the architectures that have usp in pt_regs and do not have
user_stack_pointer() already defined.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/avr32/include/asm/ptrace.h b/arch/avr32/include/asm/ptrace.h
index 8d3c412..630e4f9 100644
--- a/arch/avr32/include/asm/ptrace.h
+++ b/arch/avr32/include/asm/ptrace.h
@@ -21,6 +21,7 @@
 #define user_mode(regs)                 (((regs)->sr & MODE_MASK) == MODE_USER)
 #define instruction_pointer(regs)       ((regs)->pc)
 #define profile_pc(regs)                instruction_pointer(regs)
+#define user_stack_pointer(regs)	((regs)->sp)
 
 static __inline__ int valid_user_regs(struct pt_regs *regs)
 {