tools/testing/nvdimm: unit test clear-error commands

[ Upstream commit fb2a1748355161e050e9f49f1ea9a0ae707a148b ]

Validate command parsing in acpi_nfit_ctl for the clear error command.
This tests for a crash condition introduced by commit 4b27db7e26cd
"acpi, nfit: add support for the _LSI, _LSR, and _LSW label methods".

Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>