nvdimm/namespace: drop nested variable in create_namespace_pmem()

Kernel build bot reported:

  namespace_devs.c:1991:10: warning: Local variable 'uuid' shadows outer variable [shadowVariable]

Refactor create_namespace_pmem() by dropping a nested version of
the same variable.

Fixes: d1c6e08 ("libnvdimm/labels: Add uuid helpers")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220607164937.33967-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Author: andy-shev

drivers/nvdimm/namespace_devs.c

@@ -1712,8 +1712,6 @@ static struct device *create_namespace_pmem(struct nd_region *nd_region,
 	res->flags = IORESOURCE_MEM;
 
 	for (i = 0; i < nd_region->ndr_mappings; i++) {
-		uuid_t uuid;
-
 		nsl_get_uuid(ndd, nd_label, &uuid);
 		if (has_uuid_at_pos(nd_region, &uuid, cookie, i))
 			continue;