drm/xe: Fix kconfig prompt

The xe driver is the official driver for Intel Xe2 and later, while
maintaining experimental support for earlier GPUs. Reword the help
message accordingly.

Reviewed-by: Maarten Lankhorst <dev@lankhorst.se>
Link: https://lore.kernel.org/r/20250611-xe-kconfig-help-v1-1-8bcc6b47d11a@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
(cherry picked from commit 1488a3089de3d0bcdc9532da7ce04cf0af9d7dd0)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>