i2c: designware: Combine the init functions

i2c: designware: Combine the init functions

Providing a single function for controller initialisation.
The controller initialisation has the same steps for master
and slave modes, except the timing parameters are only
needed in master mode.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260120130729.1679560-3-heikki.krogerus@linux.intel.com