test/py: scsi: Add test for scsi commands

Add a following test cases for scsi commands:
scsi_reset - To reset SCSI controller
scsi_info - To show available SCSI devices
scsi_scan - To (re-)scan SCSI bus
scsi_device - To show or set surrent device
scsi_part - To print partition table of selected SCSI device

Signed-off-by: Love Kumar <love.kumar@amd.com>