[SCSI] aha152x, eata, u14-34f: minor irq handler cleanups

- remove pointless casts from void*

- remove needless references to 'irq' function argument, when that
  information is already stored somewhere in a driver-private struct.

- where the 'irq' function argument is known never to be used, rename
  it to 'dummy' to make this more obvious

- remove always-false tests for dev_id==NULL

- remove always-true tests for 'irq == host_struct->irq'

- replace per-irq lookup functions and tables with a direct reference
  to data object obtained via 'dev_id' function argument, passed from
  request_irq()

This change's main purpose is to prepare for the patchset in
jgarzik/misc-2.6.git#irq-remove, that explores removal of the
never-used 'irq' argument in each interrupt handler.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/scsi/u14-34f.c b/drivers/scsi/u14-34f.c
index 58d7eee..640333b 100644
--- a/drivers/scsi/u14-34f.c
+++ b/drivers/scsi/u14-34f.c
@@ -1715,13 +1715,12 @@
 
 }
 
-static irqreturn_t ihdlr(int irq, unsigned int j) {
+static irqreturn_t ihdlr(unsigned int j)
+{
    struct scsi_cmnd *SCpnt;
    unsigned int i, k, c, status, tstatus, reg, ret;
    struct mscp *spp, *cpp;
-
-   if (sh[j]->irq != irq)
-       panic("%s: ihdlr, irq %d, sh[j]->irq %d.\n", BN(j), irq, sh[j]->irq);
+   int irq = sh[j]->irq;
 
    /* Check if this board need to be serviced */
    if (!((reg = inb(sh[j]->io_port + REG_SYS_INTR)) & IRQ_ASSERTED)) goto none;
@@ -1935,7 +1934,7 @@
    if ((j = (unsigned int)((char *)shap - sha)) >= num_boards) return IRQ_NONE;
 
    spin_lock_irqsave(sh[j]->host_lock, spin_flags);
-   ret = ihdlr(irq, j);
+   ret = ihdlr(j);
    spin_unlock_irqrestore(sh[j]->host_lock, spin_flags);
    return ret;
 }