media: dvb: Fix recording with multiple PIDs

A recording pipe can have multiple feeds associated to it, one of which
is considered to be the pipe's parent feed. In case the parent feed is
closed and pipe handler is called an invalid parent feed will be used.
To avoid such case, the parent feed will be updated with another valid
feed in case the current parent feed is closed.

Change-Id: Iadcc7e346aad84958cd8c8bcc4e282779251c591
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>