drm/xe/i2c: Introduce xe_i2c_present()

drm/xe/i2c: Introduce xe_i2c_present()

In preparation of wider usecases which require checking for I2C
controller presence, introduce xe_i2c_present() helper.

v2: Doc fix (Riana)

Suggested-by: Riana Tauro <riana.tauro@intel.com>
Signed-off-by: Raag Jadav <raag.jadav@intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Riana Tauro <riana.tauro@intel.com>
Link: https://lore.kernel.org/r/20250814091845.1356135-1-raag.jadav@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>