x86/amd-iommu: Move find_protection_domain to helper functions
x86/amd-iommu: Move find_protection_domain to helper functions

This is a helper function and when its placed in the helper
function section we can remove its forward declaration.

Signed-off-by: Joerg Roedel <ebd221a096cbc71dd9e1991db28795933c85f380@amd.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs