megaraid: fix irq setup process regression

megaraid: fix irq setup process regression

Orabug: 22620626

This fixes a regression caused by commit
d3557fc8be11d25f316884581f487684f8e7dad3 megaraid_sas : Add separate function
for setting up IRQs This makes boot end with 'root does not exist' message on
certain adapters.

The bug is that the driver does not setup ints for cards without msi-x
support.  This patch fixes it, in addition to that it moves tasklet
initialisation before enable_intr, otherwise a kernel panic may occur, when an
interrupt arrives before the tasklet is ready.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Sumit Saxena <sumit.saxena@avagotech.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
(cherry picked from commit 258c3af2b9309412d82e74b2ea87e8c140fe2072)
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>