RawImageCreator: remove meter for hash calculation

RawImageCreator: remove meter for hash calculation

We currently use the progress meter when calculating hash functions
of the raw image file. Well, there is nothing bad with this, but this
is not really necessary. I am removing this because I am going to
introduce a helper function for calculating hashes, and I do not want
to complicate it with a meter.

So, remove the meter. We can add it back if we find this necessary
in the future.

This makes the code a bit less complex as well.

Change-Id: I7da651f82dcbb14e16e1dccbbc4ee73cc1aa7e0b
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@intel.com>