V4L/DVB (7286): limit stack usage of ir-kbd-i2c.c

ir_probe allocated struct i2c_client on stack;
it's pretty big structure, so allocate it with kzalloc

make checkstack output without this patch:
x059d ir_probe [ir-kbd-i2c]:                           1000

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>