MIPS: Loongson64: sleeper: Pass ra and sp as arguments

Some firmware implementations require restoring ra and sp to be
passed as arguments.

Passing them as necessary.

Fixes: 68557c59 ("MIPS: Loongson64: Implement PM suspend for LEFI firmware")
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>