[XEN PATCH 2/5] iommu: address violation of MISRA C Rule 5.5

[Dmytro Prokopchuk1 <dmytro_prokopchuk1@xxxxxxxx>]

Address a violation of MISRA C:2012 Rule 5.5:
"Identifiers shall be distinct from macro names".

Reports for service MC3A2.R5.5:
xen/include/xen/iommu.h: non-compliant struct 'page_list_head'
xen/include/xen/mm.h: non-compliant macro 'page_list_head'
xen/drivers/passthrough/iommu.c: non-compliant macro 'iommu_quarantine'
xen/include/xen/iommu.h: non-compliant variable 'iommu_quarantine'

These external variables ('iommu_pt_cleanup_lock'
and 'iommu_pt_cleanup_list') are no longer used
in the codebase. Removing them eliminates dead
code and ensures compliance with coding standards.
Fixes: b5622eb627 (iommu: remove unused iommu_ops method and tasklet, 
2020-09-22)

The variable 'iommu_quarantine' makes sence to use
only if 'CONFIG_HAS_PCI=y', so place it inside '#ifdef'.

Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>
---
 xen/include/xen/iommu.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index ebfada1d88..57f338e2a0 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -53,7 +53,9 @@ static inline bool dfn_eq(dfn_t x, dfn_t y)
 extern bool iommu_enable, iommu_enabled;
 extern bool force_iommu, iommu_verbose;
 /* Boolean except for the specific purposes of drivers/passthrough/iommu.c. */
+#ifdef CONFIG_HAS_PCI
 extern uint8_t iommu_quarantine;
+#endif /* CONFIG_HAS_PCI */
 #else
 #define iommu_enabled false
 #endif
@@ -500,9 +502,6 @@ void iommu_dev_iotlb_flush_timeout(struct domain *d, struct 
pci_dev *pdev);
  */
 DECLARE_PER_CPU(bool, iommu_dont_flush_iotlb);
 
-extern struct spinlock iommu_pt_cleanup_lock;
-extern struct page_list_head iommu_pt_cleanup_list;
-
 bool arch_iommu_use_permitted(const struct domain *d);
 
 #ifdef CONFIG_X86
-- 
2.43.0