keymaster: 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

/cc @JulienMasson @eblanc @glaroque

Bug: TIAU-501