ptrace: cleanup arch_ptrace() on um

Remove unnecessary castings using void pointer and fix copy_to_user()
return value. Also add missing __user markup on the argument of
arch_ptrctl().

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/sys-x86_64/ptrace.c b/arch/um/sys-x86_64/ptrace.c
index 67e6368..f436136 100644
--- a/arch/um/sys-x86_64/ptrace.c
+++ b/arch/um/sys-x86_64/ptrace.c
@@ -179,15 +179,14 @@
 		    unsigned long addr, unsigned long data)
 {
 	int ret = -EIO;
+	void __user *datap = (void __user *) data;
 
 	switch (request) {
 	case PTRACE_GETFPXREGS: /* Get the child FPU state. */
-		ret = get_fpregs((struct user_i387_struct __user *) data,
-				 child);
+		ret = get_fpregs(datap, child);
 		break;
 	case PTRACE_SETFPXREGS: /* Set the child FPU state. */
-		ret = set_fpregs((struct user_i387_struct __user *) data,
-				 child);
+		ret = set_fpregs(datap, child);
 		break;
 	}