sparc64: Remvoe set_fs() from perf_callchain_user().

Ever since commit 88b0193d ("perf/callchain: Force USER_DS when
invoking perf_callchain_user()") the caller does this for us.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/sparc/kernel/perf_event.c

@@ -1849,16 +1849,12 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
 {
 	u64 saved_fault_address = current_thread_info()->fault_address;
 	u8 saved_fault_code = get_thread_fault_code();
-	mm_segment_t old_fs;
 
 	perf_callchain_store(entry, regs->tpc);
 
 	if (!current->mm)
 		return;
 
-	old_fs = get_fs();
-	set_fs(USER_DS);
-
 	flushw_user();
 
 	pagefault_disable();
@@ -1870,7 +1866,6 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
 
 	pagefault_enable();
 
-	set_fs(old_fs);
 	set_thread_fault_code(saved_fault_code);
 	current_thread_info()->fault_address = saved_fault_address;
 }