staging: unisys: visorhba: Convert module from IDR to XArray

staging: unisys: visorhba: Convert module from IDR to XArray

Converted visorhba from IDR to XArray. The abstract data type XArray is
more memory-efficient, parallelizable, and cache friendly. It takes
advantage of RCU to perform lookups without locking. Furthermore, IDR is
deprecated because XArray has a better (cleaner and more consistent)
API.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20210514081112.19542-1-fmdefrancesco@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>