S2io: Removed unused feature - bimodal interrupts

Removed bimodal interrupt support - unused feature

Signed-off-by: Sivakumar Subramani <sivakumar.subramani@neterion.com>
Signed-off-by: Ramkrishna Vepa <ram.vepa@neterion.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

[also, trim trailing whitespace]