sw64: fix floating point register corruption

Sunway inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5GFS3



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When csum_partial_copy_from_user is called in an interrupt,
__copy_from_user will modify floating point register f10-f15
without restore register value. This will cause the value of
the userspace register to be corrupted. Use memcpy() instead
when called from kernel space.

Signed-off-by: Zhou Xuemei <zhouxuemei@wxiat.com>

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