arm64: Use page_to_pvh() instead of pa_to_pvh() when the vm_page_t is known

[alc]

Summary

When support for a sparse pv_table was added, the implementation of pa_to_pvh() changed from a simple constant-time calculation to iterating over the vm_phys_segs array. To mitigate this issue, an alternative function, page_to_pvh(), was introduced that still runs in constant time but requires the vm_page_t to be known. However, three cases where the vm_page_t is known were not converted to page_to_pvh(). This change converts those cases.