python: Manually convert float to int when using %x

python: Manually convert float to int when using %x

This is required by python3.5 which is not allowing a
floating point value to be printed in hex and will trigger
a TypeError assertion:

TypeError: %X format: an integer is required, not float

Change-Id: I2033366751924579cc87e7fccda8fdb33a31412d
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28607
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>