It turns out the code for the firmware size validation was incorrectly
using the total length of the firmware file to check if it was too big
for the flash rom which caused it to incorrectly flag larger bootloaders
as too big even though they would still fit.
As it happens this situation can only really arise after mkboot has been
run on the decoded firmware image. Because mkboot writes the actual binary
size to the ESTFBINR header we will be using that to check if the firmware
image is too large for the flash rom.
Now because this information is embedded in the decrypted / encrypted
region we have to collect it as the region is processed so the validation
is also moved to after the data processing loop.
Change-Id: I8bfead73812fe4e59f08fbbe8956790604dcb4e2
