scsi: csiostor: update csio_get_flash_params()

- Updates csio_get_flash_params() to take care of ISSI, Macronix and
  Winbond FLASH parts.

- Assume flash part size to be 4MB if it cannot be identified

Signed-off-by: Arjun Vynipadath <arjun@chelsio.com>
Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>