megaraid_sas: task management code optimizations

This patch will do code optmization for task management functions.
Below are key changes:

1. Remove reset_device hook as it was not being used and driver was
setting this to NULL.

2. Create wrapper functions for task abort and target reset and inside
   these functions adapter specific calls be made. e.g. fusion adapters
   support task abort and target reset so task abort and target reset
   should be issued to fusion adapters only and for MFI adapters, print
   a message saying feature not supported.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Reviewed-by: Hannes Reinicke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>