FROMLIST: scsi: ufs: Region inactivation in HCM

In host mode, the host is expected to send HPB-WRITE-BUFFER with
buffer-id = 0x1 when it inactivates a region.

Use the map-requests pool as there is no point in assigning a
designated cache for umap-requests.

Bug: 183467926
Bug: 170940265
Bug: 183454255

Link: https://lore.kernel.org/lkml/20210607061401.58884-7-avri.altman@wdc.com/


Signed-off-by: Avri Altman <avri.altman@wdc.com>
Change-Id: I1a6696b38d4abfb4d9fbe44e84016a6238825125