Do not use PAGE_SIZE marco to calculate max_sectors per I/O
request. Driver code assumes PAGE_SIZE will be always 4096 which can
lead to wrongly calculated value if PAGE_SIZE is not 4096. This issue
was reported in Ubuntu Bugzilla Bug #1475166.

Cc: <stable@vger.kernel.org>
Signed-off-by: NSumit Saxena <sumit.saxena@avagotech.com>
Signed-off-by: NKashyap Desai <kashyap.desai@avagotech.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>