Currently the comparison of end with less than zero is always false
because end is an unsigned long.  Also, replace checks of end with
non-zero with end > 0 as it is possible that the #defined decrement may be
changed in the future causing end to step over zero and go negative.

The initialization of end with 0 is also redundant as this value is never
read and is later set to HW_SYNC_TIMEOUT_MSECS, so fix this by
initializing it with this value to begin with.

Link: https://lore.kernel.org/r/20190531092101.28772-1-colin.king@canonical.com
Addresses-Coverity: ("Unsigned compared against 0")
Fixes: 669cefb6 ("RDMA/hns: Remove jiffies operation in disable interrupt context")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>