V4L/DVB: media/video/tlg2300: fix build when CONFIG_PM=n

When CONFIG_PM is not enabled, tlg2300 has build errors,
so handle that case, mostly via stubs.

drivers/media/video/tlg2300/pd-alsa.c:237: error: 'struct poseidon' has no member named 'msg'
drivers/media/video/tlg2300/pd-main.c:412: error: implicit declaration of function 'find_old_poseidon'
drivers/media/video/tlg2300/pd-main.c:418: error: implicit declaration of function 'set_map_flags'
drivers/media/video/tlg2300/pd-main.c:462: error: implicit declaration of function 'get_pd'

Cc: linux-next@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>, 	linux-media@vger.kernel.org
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Huang Shijie <shijie8@gmail.com>
Cc: Kang Yong <kangyong@telegent.com>
Cc: Zhang Xiaobing <xbzhang@telegent.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>