i2c: constify i2c_adapter_quirks structures

Check for i2c_adapter_quirks structures that are only stored in the
quirks field of an i2c_adapter structure.  This field is declared
const, so i2c_adapter_quirks structures that have this property can be
declared as const also.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Ray Jui <ray.jui@broadcom.com> # for bcm-iproc
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>