[PATCH] make use of 'uts_namespace.name' offset in VMCOREINFO

* Required for kernel 5.11

The offset of the field 'init_uts_ns.name' has changed since
kernel commit 9a56493f6942 ("uts: Use generic ns_common::count").
Make use of the offset 'uts_namespace.name' if available in
VMCOREINFO.

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>