ufs: manually add well known logical units

UFS device specification requires the UFS devices to support 4 well known
logical units:
	"REPORT_LUNS" (address: 01h)
	"UFS Device" (address: 50h)
	"RPMB" (address: 44h)
	"BOOT" (address: 30h)

UFS device's power management needs to be controlled by "POWER CONDITION"
field of SSU (START STOP UNIT) command. But this "power condition" field
will take effect only when its sent to "UFS device" well known logical unit
hence we require the scsi_device instance to represent this logical unit in
order for the UFS host driver to send the SSU command for power management.

We also require the scsi_device instance for "RPMB" (Replay Protected
Memory Block) LU so user space process can control this LU. User space may
also want to have access to BOOT LU.

This patch adds the scsi device instances for each of all well known LUs
(except "REPORT LUNS" LU).

Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Dolev Raviv <draviv@codeaurora.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>