i2c-algo-pca: Remove trailing whitespaces and unnecessary UTF

Remove trailing whitespaces to make further patches more readable.  Also remove
an unnecessary UTF-char for simplicity ("us" for microseconds is fine enough).

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>