regulator: tps65023: Remove duplicate test for I2C_FUNC_SMBUS_BYTE_DATA functionality

Since commit b4226107 ("regmap: i2c: fallback to SMBus if the adapter
does not support standard I2C"), regmap-i2c will check the
I2C_FUNC_SMBUS_[BYTE|WORD]_DATA functionality based on the regmap_config
setting if the adapter does not support standard I2C.

So remove the I2C_FUNC_SMBUS_BYTE_DATA functionality check in the driver code.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>