Currently, there are two module parameters for the i2c driver:
- polling_req: boolean irq/polling mode;
- scan_rate: polling rate, that is used in the case where the polling
mode is active
This model is misconfiguration-prone. For example, it is possible to
select polling mode with the zero polling rate or configure non-zero
polling rate in a combination with the IRQ mode.
This patch replaces the 'polling_req' and 'scan_rate' by the
'polling_rate', where the value zero means the interrupt driven mode and
other values are used as the polling rate in the polling mode.