i2c: designware: Consolidate firmware parsing and configuring code

We have the same code flows in the PCI and platform drivers. Moreover,
the flow requires the common code to export a few functions. Instead,
consolidate that flow under new function called
i2c_dw_fw_parse_and_configure() and drop unneeded exports.

Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>