device-dax: Fix default return code of range_parse()

device-dax: Fix default return code of range_parse()

[ Upstream commit 7323fb22f05ff1d20498d267828870a5fbbaebd6 ]

The return value of range_parse() indicates the size when it is
positive.  The error code should be negative.

Signed-off-by: Shiyang Ruan <ruansy.fnst@cn.fujitsu.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Link: https://lore.kernel.org/r/20210126021331.1059933-1-ruansy.fnst@cn.fujitsu.com
Reported-by: Zhang Qilong <zhangqilong3@huawei.com>
Fixes: 8490e2e25b5a ("device-dax: add a range mapping allocation attribute")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>