staging: vc04_services: vchiq_arm: Drop g_cache_line_size

The cache-line-size is cached in struct vchiq_platform_info.
There is no need to cache this again via g_cache_line_size
and use it. Instead use the value from vchiq_platform_info directly.

While at it, move the comment about L2 cache line size in the kerneldoc
block of struct vchiq_platform_info.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
Link: https://lore.kernel.org/r/20240412075743.60712-4-umang.jain@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>