rtc: rv3029: remove 'i2c' in functions names

To prepare the use of regmap to add the support of RV-3049, all the
'i2c' in functions's names are removed.

Signed-off-by: Mylène Josserand <mylene.josserand@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>