um: Correctly check for PTRACE_GETRESET/SETREGSET

When checking for PTRACE_GETRESET/SETREGSET, make sure that
the correct header file is included. We need linux/ptrace.h
which contains all ptrace UAPI related defines.
Otherwise #if defined(PTRACE_GETRESET) is always false.

Cc: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/x86/um/user-offsets.c

@@ -5,7 +5,7 @@
 #include <sys/mman.h>
 #include <sys/user.h>
 #define __FRAME_OFFSETS
-#include <asm/ptrace.h>
+#include <linux/ptrace.h>
 #include <asm/types.h>
 
 #ifdef __i386__