sw64: bpf: fix 32-bit bitwise operation

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5PNI5



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Make sure the result of 32-bit bitwise operation is zero extended to
64 bits.

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