ANDROID: Fix mmu_notifier imbalance

SPF patchset introduced an mmu_notifier imbalance by adding a new exit
path that skips mmu_notifier_invalidate_range_only_end after calling
mmu_notifier_invalidate_range_start. This triggers a BUG in KVM driver
checking for mmu_notifier_count to remain balanced

Fixes: afeec97a ("FROMLIST: mm: prepare for FAULT_FLAG_SPECULATIVE")
Bug: 161210518
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: Ibe9d1f0903a23b48c9d733b81249b190e5321c2f