i2c: designware: Fix the functionality flags of the slave-only interface

i2c: designware: Fix the functionality flags of the slave-only interface

When an I2C adapter acts only as a slave, it should not claim to
support I2C master capabilities.

Fixes: 5b6d721b266a ("i2c: designware: enable SLAVE in platform module")
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Luis Oliveira <lolivei@synopsys.com>
Cc: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Jan Dabros <jsd@semihalf.com>
Cc: Andi Shyti <andi.shyti@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>