scsi: bfa: Double-free fix

When the bfad_im_probe() function fails during initialization, the memory
pointed to by bfad->im is freed without setting bfad->im to NULL.

Subsequently, during driver uninstallation, when the state machine enters
the bfad_sm_stopping state and calls the bfad_im_probe_undo() function,
it attempts to free the memory pointed to by bfad->im again, thereby
triggering a double-free vulnerability.

Set bfad->im to NULL if probing fails.

Signed-off-by: jackysliu <1972843537@qq.com>
Link: https://lore.kernel.org/r/tencent_3BB950D6D2D470976F55FC879206DE0B9A09@qq.com


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>