staging: ath6kl: Convert type of streamExists to A_UINT8

Make the declaration type match the assigned from type.
It's not a bool, it's a u8.

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Vipin Mehta <vipin.mehta@atheros.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>