Staging: vt6656: use ARRAY_SIZE macro in channel.c

Replace (sizeof(ChannelRuleTab) / sizeof(ChannelRuleTab[0])) with
ARRAY_SIZE(ChannelRuleTab) in drivers/staging/vt6656/channel.c

Signed-off-by: Nikitas Angelinas <nikitasangelinas@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>