media: gspca: make array st6422_bridge_init static, makes object smaller

Don't populate the array st6422_bridge_init on the stack but instead
make it static. Makes the object code smaller by 231 bytes.

Before:
   text	   data	    bss	    dec	    hex	filename
   3419	    752	     64	   4235	   108b	gspca/stv06xx/stv06xx_st6422.o

After:
   text	   data	    bss	    dec	    hex	filename
   3124	    816	     64	   4004	    fa4	gspca/stv06xx/stv06xx_st6422.o

(gcc version 9.2.1, amd64)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>