scsi: hpsa: Strip out a bunch of set but unused variables

scsi: hpsa: Strip out a bunch of set but unused variables

Fixes the following W=1 kernel build warning(s):

 drivers/scsi/hpsa.c: In function ‘hpsa_volume_offline’:
 drivers/scsi/hpsa.c:3885:5: warning: variable ‘scsi_status’ set but not used [-Wunused-but-set-variable]
 drivers/scsi/hpsa.c:3884:6: warning: variable ‘cmd_status’ set but not used [-Wunused-but-set-variable]
 drivers/scsi/hpsa.c: In function ‘hpsa_update_scsi_devices’:
 drivers/scsi/hpsa.c:4354:9: warning: variable ‘n_ext_target_devs’ set but not used [-Wunused-but-set-variable]
 drivers/scsi/hpsa.c: In function ‘hpsa_scatter_gather’:
 drivers/scsi/hpsa.c:4583:36: warning: variable ‘last_sg’ set but not used [-Wunused-but-set-variable]
 drivers/scsi/hpsa.c: In function ‘hpsa_init_one’:
 drivers/scsi/hpsa.c:8639:6: warning: variable ‘dac’ set but not used [-Wunused-but-set-variable]
 drivers/scsi/hpsa.c: In function ‘hpsa_enter_performant_mode’:
 drivers/scsi/hpsa.c:9300:7: warning: variable ‘rc’ set but not used [-Wunused-but-set-variable]

Link: https://lore.kernel.org/r/20201112101929.GC1997862@dell
Cc: Don Brace <don.brace@microchip.com>
Cc: Bugfixes to <esc.storagedev@microsemi.com>
Cc: storagedev@microchip.com
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>