drm/panthor: Add panthor_hw and move gpu_info initialization into it

drm/panthor: Add panthor_hw and move gpu_info initialization into it

This patch introduces panthor_hw and moves the initialization of the
gpu_info struct into panthor_hw.c in preparation of handling future GPU
register and naming changes.

Future GPU support can be added by extending panthor_gpu_info_init()
with the necessary register reads behind GPU architecture version guards
if the change is minor. For more complex changes, the function can be
forked and the appropriate function will need to be called based on the
GPU architecture version.

Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Karunika Choo <karunika.choo@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20250807162633.3666310-2-karunika.choo@arm.com