[SCSI] megaraid: Use the proper type to hold the irq number.

When testing on a Unisys machine it was discovered that the megaraid driver
would not initialize as it was requesting irq 162 instead of irq 1442 it
was assigned.  The problem was the irq number had been truncated by being
stored in an unsigned char.

This patches fixes that problem and the driver now appears to work.

The ioctl interface appears fundamentally broken as it exports the irq
number to user space in an unsigned char.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>