android: persistent_ram: Include ecc_size when calculating ecc_block

Wastes less memory and allows using more memory for ecc than data.

Change-Id: I1537d28ef3e8626e2dfdc69f2e185d28b7600916
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: garwedgess <garethwilliams21@gmail.com>