cxl/region: Fix x1 root-decoder granularity calculations

cxl/region: Fix x1 root-decoder granularity calculations

Root decoder granularity must match value from CFWMS, which may not
be the region's granularity for non-interleaved root decoders.

So when calculating granularities for host bridge decoders, use the
region's granularity instead of the root decoder's granularity to ensure
the correct granularities are set for the host bridge decoders and any
downstream switch decoders.

Test configuration is 1 host bridge * 2 switches * 2 endpoints per switch.

Region created with 2048 granularity using following command line:

cxl create-region -m -d decoder0.0 -w 4 mem0 mem2 mem1 mem3 \
		  -g 2048 -s 2048M

Use "cxl list -PDE | grep granularity" to get a view of the granularity
set at each level of the topology.

Before this patch:
        "interleave_granularity":2048,
        "interleave_granularity":2048,
    "interleave_granularity":512,
        "interleave_granularity":2048,
        "interleave_granularity":2048,
    "interleave_granularity":512,
"interleave_granularity":256,

After:
        "interleave_granularity":2048,
        "interleave_granularity":2048,
    "interleave_granularity":4096,
        "interleave_granularity":2048,
        "interleave_granularity":2048,
    "interleave_granularity":4096,
"interleave_granularity":2048,

Fixes: 27b3f8d13830 ("cxl/region: Program target lists")
Cc: <stable@vger.kernel.org>
Signed-off-by: Jim Harris <jim.harris@samsung.com>
Link: https://lore.kernel.org/r/169824893473.1403938.16110924262989774582.stgit@bgt-140510-bm03.eng.stellus.in
[djbw: fixup the prebuilt cxl_test region]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>