Instead of trying to fit two rather different cases into a single
loop, split digesting memory and digesting files into separate
subroutines. While duplicating some of the code shared by both of the
while() loops this makes the body of the loop easier to follow as well
as gets rid of poorly named "flags" variable.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>