accel/qaic: Replace kzalloc + copy_from_user with memdup_user

accel/qaic: Replace kzalloc + copy_from_user with memdup_user

Replace kzalloc() followed by copy_from_user() with memdup_user() to
improve and simplify qaic_attach_slice_bo_ioctl().

No functional changes intended.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Reviewed-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>
Signed-off-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250917124805.90395-2-thorsten.blum@linux.dev