scsi: megaraid_sas: Remove a bunch of set but not used variables

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/scsi/megaraid/megaraid_sas_fusion.c: In function 'wait_and_poll':
drivers/scsi/megaraid/megaraid_sas_fusion.c:936:25: warning:
 variable 'fusion' set but not used [-Wunused-but-set-variable]

drivers/scsi/megaraid/megaraid_sas_fusion.c: In function 'megasas_sync_map_info':
drivers/scsi/megaraid/megaraid_sas_fusion.c:1329:6: warning:
 variable 'size_sync_info' set but not used [-Wunused-but-set-variable]

drivers/scsi/megaraid/megaraid_sas_fusion.c: In function 'megasas_init_adapter_fusion':
drivers/scsi/megaraid/megaraid_sas_fusion.c:1639:39: warning:
 variable 'reg_set' set but not used [-Wunused-but-set-variable]

drivers/scsi/megaraid/megaraid_sas_fusion.c: In function 'megasas_is_prp_possible':
drivers/scsi/megaraid/megaraid_sas_fusion.c:1925:25: warning:
 variable 'fusion' set but not used [-Wunused-but-set-variable]

drivers/scsi/megaraid/megaraid_sas_fusion.c: In function 'megasas_make_prp_nvme':
drivers/scsi/megaraid/megaraid_sas_fusion.c:2047:25: warning:
 variable 'fusion' set but not used [-Wunused-but-set-variable]

drivers/scsi/megaraid/megaraid_sas_fusion.c: In function 'megasas_build_ldio_fusion':
drivers/scsi/megaraid/megaraid_sas_fusion.c:2620:42: warning:
 variable 'req_desc' set but not used [-Wunused-but-set-variable]

drivers/scsi/megaraid/megaraid_sas_fusion.c: In function 'megasas_build_and_issue_cmd_fusion':
drivers/scsi/megaraid/megaraid_sas_fusion.c:3245:25: warning:
 variable 'fusion' set but not used [-Wunused-but-set-variable]

drivers/scsi/megaraid/megaraid_sas_fusion.c: In function 'megasas_task_abort_fusion':
drivers/scsi/megaraid/megaraid_sas_fusion.c:4398:25: warning:
 variable 'fusion' set but not used [-Wunused-but-set-variable]

drivers/scsi/megaraid/megaraid_sas_fusion.c: In function 'megasas_reset_target_fusion':
drivers/scsi/megaraid/megaraid_sas_fusion.c:4484:25: warning:
 variable 'fusion' set but not used [-Wunused-but-set-variable]

They're not used anymore and can be removed.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>