i2c: imx-lpi2c: use bulk clk API

The current driver only support one clock, however LPI2C requires
two clocks: PER and IPG.

To make sure old dts could work with newer kernel, use bulk clk
API.

Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>