hpt366: add debounce delay to cable_detect() method

Alan Cox reported that cable detection sometimes works unreliably
for HPT3xxN and that the issue is fixed by adding debounce delay
as used by the vendor drivers.

While at it, get rid of unneeded parens/space in the vicinity...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>