iommu/vt-d: Remove redundant assignment to variable err

iommu/vt-d: Remove redundant assignment to variable err

Variable err is being assigned a value that is never read. It is
either being re-assigned later on error exit paths, or never referenced
on the non-error path.

Cleans up clang scan build warning:
drivers/iommu/intel/dmar.c:1070:2: warning: Value stored to 'err' is
never read [deadcode.DeadStores]`

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20240411090535.306326-1-colin.i.king@gmail.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>