TI: plugin_store: Remove use of hardcoded PAGE_SIZE 4096

bionic hard-codes the PAGE_SIZE macro as 4096. This is going away as
Android begins to support larger page sizes [1]

Remove the usage of this hard-coded value by using getpagesize() instead
as recommended by the doc [2].

[1] https://source.android.com/docs/core/architecture/16kb-page-size/16kb
[2] https://source.android.com/docs/core/architecture/16kb-page-size/getting-page-size


Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

plugin_store/C2CarveoutDmaBufAllocator.cpp

@@ -171,6 +171,7 @@ class C2CarveoutDmaBufAllocation : public C2LinearAllocation {
 
 c2_status_t C2CarveoutDmaBufAllocation::map(size_t offset, size_t size, C2MemoryUsage usage, C2Fence* fence,
                                     void** addr) {
+    static const size_t kPageSize = getpagesize();
     (void)fence;  // TODO: wait for fence
     *addr = nullptr;
     if (!mMappings.lock()->empty()) {
@@ -193,7 +194,7 @@ c2_status_t C2CarveoutDmaBufAllocation::map(size_t offset, size_t size, C2Memory
         prot |= PROT_WRITE;
     }
 
-    size_t alignmentBytes = offset % PAGE_SIZE;
+    size_t alignmentBytes = offset % kPageSize;
     size_t mapOffset = offset - alignmentBytes;
     size_t mapSize = size + alignmentBytes;
     Mapping map = {nullptr, alignmentBytes, mapSize};