tpm: atmel_twi: Make compatible with DM I2C busses

tpm: atmel_twi: Make compatible with DM I2C busses

Commit 302c5db ("dm: tpm: Add Driver Model support for tpm_atmel_twi
driver") converted the Atmel TWI TPM driver itself to driver model, but
kept the legacy-style i2c_write/i2c_read calls.

Commit 3e7d940 ("dm: tpm: Every TPM drivers should depends on DM_TPM")
then made DM_I2C a dependency of the driver, effectively forcing users
to turn on CONFIG_DM_I2C_COMPAT to get it to work.

This patch adds the necessary dm_i2c_write/dm_i2c_read calls to make the
driver compatible with DM, but also keeps the legacy calls in ifdefs, so
that the driver is now compatible with both DM and non-DM setups.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Andreas Bießmann <andreas@biessmann.org>