On the reader size, don't assume that the property size is PA_SIZE,
read it from the size of the file. Allows init to use a different
property size without recompiling statically linked executables.
(cherry picked from commit 285b42a04cbe8e627a75c9bfb3c7cb3f7b539267)
Change-Id: I074204e9e6591b35faf7c1c58fb11ec162aff7bf