iio: common: ssp_sensors: gyro: constify iio_info structures

Check for iio_info structures that are only stored in the info field of a
iio_dev structure.  This field is declared const, so iio_info structures
that have this property can be declared as const also.

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 iio_info i@p = { ... };

@ok@
identifier r.i;
struct iio_dev e;
position p;
@@
e.info = &i@p;

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

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

The result of size on this file before the change is:
   text	      data     bss     dec         hex	  filename
   1245        344       0    1589         635
   drivers/iio/gyro/ssp_gyro_sensor.o

and after the change it is:
   text	     data        bss	    dec	    hex	filename
   1397       192          0       1589     635
   drivers/iio/gyro/ssp_gyro_sensor.o

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>