[media] c8sectpfe: don't go past channel_data array

As reported by smatch:
	drivers/media/platform/sti/c8sectpfe/c8sectpfe-core.c:365 find_channel() error: buffer overflow 'fei->channel_data' 8 <= 63

It seems that a cut-and-paste type of error occurred here:
the channel_data array size is C8SECTPFE_MAX_TSIN_CHAN, and not
C8SECTPFE_MAXCHANNEL.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>