Cleanup
Cannes / H410 support

Support STMicroelectronics chip H410 "cannes".
Is compiled using
    PLATFORM=cannes make
Create util.h to rearrange define macro
tee_acipher_rsadorep: fix handling of zero-padding in output

- Always remove leading null bytes in output buffer (previously this was done
only for PK_PRIVATE keys)
- Leave one null byte when rsa_exptmod() output is all zeroes (do not return
an empty buffer)
- Fix output buffer length check (take padding into account)