dev_pm_ops are not supposed to change at runtime. All functions
working with dev_pm_ops provided by <linux/device.h> work with
const dev_pm_ops. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   1195	    376	      0	   1571	    623	fimc-is-i2c.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   1403	    176	      0	   1579	    62b	fimc-is-i2c.o
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>