mpt3sas: Single driver module which supports both SAS 2.0 & SAS 3.0 HBAs

Modified the mpt3sas driver to have a single driver module which
supports both SAS 2.0 & SAS 3.0 HBA devices.

* Added SAS 2.0 HBA device IDs to the mpt3sas_pci_table pci table.

* Created two separate SCSI host templates for SAS2 and SAS3 HBAs so
  that, during the driver load time driver can use corresponding host
  template(based the pci device ID) while registering a scsi host
  adapter instance for that pci device.

* Registered two IOCTL devices, mpt2ctl is for SAS2 HBAs & mpt3ctl for
  SAS3 HBAs. Also updated the code to make sure that mpt2ctl device
  processes only those ioctl cmds issued for the SAS2 HBAs and mpt3ctl
  device processes only those ioctl cmds issued for the SAS3 HBAs.

* Added separate indexing for SAS2 and SAS3 HBAs.

* Replaced compile time check 'MPT2SAS_SCSI' to run time check
  'hba_mpi_version_belonged' whereever needed.

* Aliased this merged driver to mpt2sas using MODULE_ALIAS.

* Moved global varaible 'driver_name' to per adapter instance variable.

* Created two raid function template and used corresponding raid
  function templates based on the run time check
  'hba_mpi_version_belonged'.

* Moved mpt2sas_warpdrive.c file from mpt2sas to mpt3sas folder and
  renamed it as mpt3sas_warpdrive.c.

* Also renamed the functions in mpt3sas_warpdrive.c file to follow
  current driver function name convention.

* Updated the Makefile to build mpt3sas_warpdrive.o file for these
  WarpDrive-specific functions.

* Also in function mpt3sas_setup_direct_io(), used sector_div() API
  instead of division operator (which gives compilation errors on 32 bit
  machines).

* Removed mpt2sas files, mpt2sas directory & mpt3sas_module.c file.

* Added module parameter 'hbas_to_enumerate' which permits using this
  merged driver as a legacy mpt2sas driver or as a legacy mpt3sas
  driver.

  Here are the available options for this module parameter:

   0 - Merged driver which enumerates both SAS 2.0 & SAS 3.0 HBAs
   1 - Acts as legacy mpt2sas driver, which enumerates only SAS 2.0 HBAs
   2 - Acts as legacy mpt3sas driver, which enumerates only SAS 3.0 HBAs

* Removed mpt2sas entries from SCSI's Kconfig and Makefile files.

Signed-off-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>