nios2: add missing ptrace registers defines

#define PTR_IPENDING	37

#define PTR_CPUID	38

#define PTR_CTL6	39

#define PTR_CTL7	40

#define PTR_EXCEPTION	40

#define PTR_PTEADDR	41

#define PTR_TLBACC	42

#define PTR_TLBMISC	43

#define PTR_ECCINJ	44

#define PTR_BADADDR	45

#define PTR_CONFIG	46

#define PTR_MPUBASE	47

#define PTR_MPUACC	48

#define NUM_PTRACE_REG (PTR_TLBMISC + 1)

#define NUM_PTRACE_REG (PTR_MPUACC + 1)

/* User structures for general purpose registers.  */

struct user_pt_regs {