[media] media: pci: constify stv0299_config structures

Declare stv0299_config structures as const as they are only passed as
an argument to the function dvb_attach. dvb_attach
calls its first argument on the rest of its arguments. The first
argument of dvb_attach in the changed cases is stv0299_attach and
the parameter of this function to which the object references are passed
is of type const. So, stv0299_config structures having this property
can be made const.

First line shows the file size before patching and second one shows size
after patching.

   text	   data	    bss	    dec	    hex	filename
   9572	    926	     40	  10538	   292a media/pci/dm1105/dm1105.o
   9636	    862	     40	  10538	   292a media/pci/dm1105/dm1105.o

  15133	   5408	      0	  20541	   503d	media/pci/ttpci/budget-av.o
  15389	   5152	      0	  20541	   503d media/pci/ttpci/budget-av.o

  15703	   2326	     36	  18065	   4691	media/pci/ttpci/budget-ci.o
  15767	   2262	     36	  18065	   4691 media/pci/ttpci/budget-ci.o

  10555	   1918	      4	  12477	   30bd	drivers/media/pci/ttpci/budget.o
  10683	   1822	      4	  12509	   30dd	drivers/media/pci/ttpci/budget.o

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>