[media] constify i2c_algorithm structures

These i2c_algorithm structures are only stored in the alg field of an
i2c_adapter structure, which is declared as const.  This declare the
structures as const as well.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/

)

// <smpl>
@r disable optional_qualifier@
identifier i;
position p;
@@
static struct i2c_algorithm i@p = { ... };

@ok@
identifier r.i;
struct i2c_adapter e;
position p;
@@
e.alg = &i@p;

@bad@
position p != {r.p,ok.p};
identifier r.i;
@@
i@p

@depends on !bad disable optional_qualifier@
identifier r.i;
@@
static
+const
 struct i2c_algorithm i = { ... };
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>