net: hns3: cleanup some magic numbers

To make the code more readable, this patch replaces
some magic numbers with macro or sizeof operation.

Also uses macro lower_32_bits and upper_32_bits to
get bits 0-31 and 32-63 of a number, instead of
using type conversion and '>>' operation.

No functional change.

Signed-off-by: Guojia Liao <liaoguojia@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>