drm/amd/display: add oem i2c implemenation in dc

[why]
Need it for some OEM I2C devices in Nv10

[how]
Link up code to parse OEM table and expose DC interface
to access the pins

Signed-off-by: Jun Lei <Jun.Lei@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/include/grph_object_ctrl_defs.h

@@ -178,7 +178,8 @@ struct dc_firmware_info {
 	uint32_t default_engine_clk; /* in KHz */
 	uint32_t dp_phy_ref_clk; /* in KHz - DCE12 only */
 	uint32_t i2c_engine_ref_clk; /* in KHz - DCE12 only */
-
+	bool oem_i2c_present;
+	uint8_t oem_i2c_obj_id;
 
 };