clocksource: shmobile: Remove unused sh_timer_config members

The name, channel_offset, timer_bit, clockevent_rating and
clocksource_rating members are unused. Remove them.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Tested-by: Simon Horman <horms+renesas@verge.net.au>