powerpc: Remove redundant set_fs(USER_DS)

The address limit is already set in flush_old_exec() so this
set_fs(USER_DS) is redundant.
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/process.c

@@ -831,8 +831,6 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
 	unsigned long load_addr = regs->gpr[2];	/* saved by ELF_PLAT_INIT */
 #endif
 
-	set_fs(USER_DS);
-
 	/*
 	 * If we exec out of a kernel thread then thread.regs will not be
 	 * set.  Do it now.