media: xc4000: get rid of uneeded casts

Instead of doing casts, use %zd to print sizes, in order to make
smatch happier:
	drivers/media/tuners/xc4000.c:818 xc4000_fwupload() warn: argument 4 to %d specifier is cast from pointer

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>