V4L/DVB (13233): i2c_board_info can be local

Recent fixes to the em28xx and saa7134 drivers have been overzealous.
While the ir-kbd-i2c platform data indeed needs to be persistent, the
struct i2c_board_info doesn't, as it is only used by i2c_new_device().

So revert a part of the original fixes, to save some memory.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>