hw/arm/mps2-tz.c: Mark internal-only I2C buses as 'full'

hw/arm/mps2-tz.c: Mark internal-only I2C buses as 'full'

The various MPS2 boards have multiple I2C buses: typically a bus
dedicated to the audio configuration, one for the LCD touchscreen
controller, one for a DDR4 EEPROM, and two which are connected to the
external Shield expansion connector.  Mark the buses which are used
only for board-internal devices as 'full' so that if the user creates
i2c devices on the commandline without specifying a bus name then
they will be connected to the I2C controller used for the Shield
connector, where guest software will expect them.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210903151435.22379-4-peter.maydell@linaro.org