megaraid_sas: fix the problem of non-existing VD exposed to host

This patch will address the issue of SCSI device created at OS level for
non existing VD. ldTgtIdtoLd[] array has size 256 for Extended VD firmware
and 128 for legacy firmware. Accessing indices beyond array size (OS will
send TUR, INQUIRY.. commands upto device index 255), may return valid LD
value and that particular SCSI command will be SUCCESS and creating SCSI
device for non existing target(VD).

For legacy firmware (64 VD firmware), invalidates LD (by setting LD value
to 0xff) in LdTgtIdtoLd[] array for device index beyond 127, so that
invalid LD(0xff) value should be returned beyond device index beyond 127.

Cc: <stable@vger.kernel.org>
Signed-off-by: Kashyap Desai <kashyap.desai@avagotech.com>
Signed-off-by: Sumit Saxena <sumit.saxena@avagotech.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>