Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/nds32/kernel/ex-scall.S b/arch/nds32/kernel/ex-scall.S
index 36aa87e..270050f 100644
--- a/arch/nds32/kernel/ex-scall.S
+++ b/arch/nds32/kernel/ex-scall.S
@@ -19,11 +19,13 @@
 
 	la	$p0, __entry_task
 	sw	$r1, [$p0]
-	move	$p1, $r0
-	addi	$p1, $p1, #THREAD_CPU_CONTEXT
+	addi	$p1, $r0, #THREAD_CPU_CONTEXT
 	smw.bi 	$r6, [$p1], $r14, #0xb		! push r6~r14, fp, lp, sp
 	move	$r25, $r1
-	addi	$r1, $r1, #THREAD_CPU_CONTEXT
+#if defined(CONFIG_FPU)
+	call	_switch_fpu
+#endif
+	addi	$r1, $r25, #THREAD_CPU_CONTEXT
 	lmw.bi 	$r6, [$r1], $r14, #0xb		! pop r6~r14, fp, lp, sp
 	ret