iommu/vt-d: Remove set but not used variable

mainline inclusion
from mainline-v5.11-rc1
commit 405a43cc
category: bugfix
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I8C8B4
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=405a43cc00471d9f06c58704448f1a43e331826a



-------------------------------------

Intel-SIG: commit 405a43cc iommu/vt-d: Remove set but not used variable
dtlb flush
Backport SPR and EMR IOMMU PCIe related upstream bugfixes to kernel 5.10.

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/iommu/intel/iommu.c:5643:27: warning: variable 'last_pfn' set but not used [-Wunused-but-set-variable]
5643 |  unsigned long start_pfn, last_pfn;
     |                           ^~~~~~~~

This variable is never used, so remove it.

Fixes: 2a2b8eaa ("iommu: Handle freelists when using deferred flushing in iommu drivers")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20201127013308.1833610-1-baolu.lu@linux.intel.com


Signed-off-by: Will Deacon <will@kernel.org>
(cherry picked from commit 405a43cc)
Signed-off-by: Ethan Zhao <haifeng.zhao@linux.intel.com>