scsi: ufs: core: Use is_visible to control UFS unit descriptor sysfs nodes

scsi: ufs: core: Use is_visible to control UFS unit descriptor sysfs nodes

UFS Boot and Device W-LUs do not have unit descriptors and RPMB does not
support WB. Use is_visible() to control which nodes are visible and which
are not.

Signed-off-by: Bean Huo <beanhuo@micron.com>
Link: https://lore.kernel.org/r/20221025222430.277768-4-beanhuo@iokpp.de
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Arthur Simchaev <arthur.simchaev@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>