i2c: cadence: Remove unused CDNS_I2C_DATA_INTR_DEPTH define

The CDNS_I2C_DATA_INTR_DEPTH is not used in the Cadence I2C driver. Remove
it.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Reviewed-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>