[SCSI] ibmvfc: Increase cancel timeout

During cancel testing it has been shown that 15 seconds is not
nearly long enough for the VIOS to respond to a cancel under
loaded situations. Increasing this timeout to 60 seconds allows
time for the VIOS to cancel the outstanding commands and prevents
us from escalating to a full host reset, which can take much longer.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>