tcg-mips: Adjust prologue for mips64

Take stack frame parameters out from the function body.

Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Tested-by: James Hogan <james.hogan@imgtec.com>
Tested-by: YunQiang Su <wzssyqa@gmail.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Jin Guojie <jinguojie@loongson.cn>
Message-Id: <1483592275-4496-8-git-send-email-jinguojie@loongson.cn>