sw64: adjust instructions order of deep-copy_template.S

Sunway inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5PN9S



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Adjust order of instructions in deep-copy_template.S to make sure $18
always has bytes left to copy. This makes sure the return value of
copy_{to,from}_user() is correct.

Signed-off-by: Mao Minkai <maominkai@wxiat.com>
Signed-off-by: Gu Zitao <guzitao@wxiat.com>