i2c: algo: pca: Fix mode selection for PCA9665

The code currently always selects turbo mode for PCA9665, no matter which
clock frequency is configured. This is because it compares the clock frequency
against constants reflecting (boundary / 100). Compare against real boundary
frequencies to fix the problem.

Signed-off-by: Thomas Kavanagh <tkavanagh@juniper.net>
Signed-off-by: Guenter Roeck <groeck@juniper.net>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>