[ARM] Fix elf_fpregset_t

This is a fix from eons ago, which apparantly has been in the old
Rebel.com netwinder CVS for several years, and has never been
submitted upstream.

This fix allows FP registers to be correctly written to ELF core
files, as well as preventing corruption of other parts of ELF core
files caused by data on the kernel stack being overwritten.

include/asm-arm/elf.h

@@ -6,6 +6,7 @@
  */
 
 #include <asm/ptrace.h>
+#include <asm/user.h>
 #include <asm/proc/elf.h>
 #include <asm/procinfo.h>
 
@@ -18,7 +19,7 @@ typedef unsigned long elf_freg_t[3];
 #define ELF_NGREG (sizeof (struct pt_regs) / sizeof(elf_greg_t))
 typedef elf_greg_t elf_gregset_t[ELF_NGREG];
 
-typedef struct { void *null; } elf_fpregset_t;
+typedef struct user_fp elf_fpregset_t;
 
 /*
  * This is used to ensure we don't load something for the wrong architecture.