fat16: fix read and remove debug messages
fat16: fix read and remove debug messages

* fat16 code had old debug prints, get rid of that
* yaboot tried reading a file beyond the size of file, fix read
  routine to override and read only till the file-size

Signed-off-by: Nikunj A Dadhania <e2f4a5db9b4735182a88051d1e7a3599f9eac9db@linux.vnet.ibm.com>

qemu/SLOF,stefanberger/SLOF-tpm,stefanberger/SLOF-tpm,open-power-host-os/slof,stefanberger/SLOF-tpm,aik/SLOF,aik/SLOF,open-power-host-os/slof,qemu/SLOF,open-power-host-os/slof,aik/SLOF,qemu/SLOF,open-power-host-os/slof