[media] soc-camera: increase the length of clk_name on soc_of_bind()

Since in soc_of_bind() it may use the of node's full name as the clk_name,
and this full name may be longer than 32 characters, take at91 i2c sensor
as an example, length is 34 bytes:
   /ahb/apb/i2c@f8028000/camera@0x30

So this patch increase the clk_name[] array size to 64. It seems big
enough so far.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>