qlcnic: refactor Legacy interrupt handling for 83xx

o Cleanly seperate 83xx Legacy interrupt handling code from 82xx
o Update 83xx Legacy interrupt handling code to match with the spec

Signed-off-by: Himanshu Madhani <himanshu.madhani@qlogic.com>
Signed-off-by: Jitendra Kalsaria <jitendra.kalsaria@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>