sw64: fix head loop in deep-copy_template.S

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



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Fix conditional branch of head loop in deep-copy_template.S, so it will
go to simd loop properly when dst is 32 bytes aligned.

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