ANDROID: Fix build error in linker_ctx() when CONFIG_PER_VMA_LOCK=n

When CONFIG_PER_VMA_LOCK=n vma->vm_lock does not exist. Fix build error
in this configuration by avoiding vm_lock usage.

Fixes: 9381f5d6 ("ANDROID: 16K: Fallback to mmap lock for linker context VMA lookup")
Bug: 444079265
Bug: 440553914
Bug: 443296451
Change-Id: If2ece084fea8973a1cb2678e6d9b32e09f5eb079
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
(cherry picked from commit 78b358dd)
(cherry picked from commit d9542e0a)