uml - tls support: fix typo

From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>

Fix bad typo.

Luckily harmless for now, as the function is not used.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Index: linux-2.6.15/arch/um/os-Linux/tls.c
===================================================================
--- linux-2.6.15.orig/arch/um/os-Linux/tls.c
+++ linux-2.6.15/arch/um/os-Linux/tls.c
@@ -10,6 +10,10 @@
  *
  */
 
+#ifndef PTRACE_GET_THREAD_AREA
+#define PTRACE_GET_THREAD_AREA 25
+#endif
+
 #ifndef PTRACE_SET_THREAD_AREA
 #define PTRACE_SET_THREAD_AREA 26
 #endif
@@ -33,7 +37,7 @@ int os_get_thread_area(void *data, int p
 	struct user_desc *info = data;
 	int ret;
 
-	ret = ptrace(PTRACE_SET_THREAD_AREA, pid, info->entry_number,
+	ret = ptrace(PTRACE_GET_THREAD_AREA, pid, info->entry_number,
 		     (unsigned long) info);
 	if (ret < 0)
 		ret = -errno;
