MAINTAINERS: Add maintainer entry for AMD Hardware Feedback Driver

Introduce the `amd_hfi` driver into the MAINTAINERS file.
The driver will support AMD Heterogeneous Core design which provides
hardware feedback to the OS scheduler.

Moving forward, Mario will be responsible for the maintenance
and Perry will assist on review of patches related to this driver.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/20250609200518.3616080-3-superm1@kernel.org