iommu/vt-d: Mark functions as static in intel_irq_remapping.c

iommu/vt-d: Mark functions as static in intel_irq_remapping.c

Mark functions int get_irte() and ir_dev_scope_init() as static in
intel_irq_remapping.c because they are not used outside this file.

This eliminates the following warnings in intel_irq_remapping.c:
drivers/iommu/intel_irq_remapping.c:49:5: warning: no previous prototype for ‘get_irte’ [-Wmissing-prototypes]
drivers/iommu/intel_irq_remapping.c:810:12: warning: no previous prototype for ‘ir_dev_scope_init’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Joerg Roedel <joro@8bytes.org>