um: Remove update_debugregs()

This function is nowhere used, let's get rid of it.
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/x86/um/shared/sysdep/ptrace_32.h

@@ -8,8 +8,6 @@
 
 #define MAX_FP_NR HOST_FPX_SIZE
 
-static inline void update_debugregs(int seq) {}
-
 void set_using_sysemu(int value);
 int get_using_sysemu(void);
 extern int sysemu_supported;