gen_hashed_bin: use integer division operator
gen_hashed_bin: use integer division operator

Use // instead of /, so this script will be compatible
with both python2 and python3.

Signed-off-by: Volodymyr Babchuk <07adff7e050dc3230ac0b7d9c296bbb62f4ecc95@gmail.com>
Acked-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>
Reviewed-by: Joakim Bech <741f90e2a7f4d9afbad8bd50be20560f4cf38962@linaro.org>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os