amd-iommu: remove amd_iommu_size kernel parameter

This parameter is not longer necessary when aperture increases
dynamically.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

diff --cc Documentation/kernel-parameters.txt
Simple merge

diff --cc arch/x86/kernel/amd_iommu.c
Simple merge

diff --cc arch/x86/kernel/amd_iommu_init.c
Simple merge