media: go7007: remove redundant initialization

In go7007_alloc() kzalloc() is used for struct go7007
allocation. It means that there is no need in zeroing
any members, because kzalloc will take care of it.

Removing these reduntant initialization steps increases
execution speed a lot:

	Before:
		+ 86.802 us   |    go7007_alloc();
	After:
		+ 29.595 us   |    go7007_alloc();

Fixes: 866b8695 ("Staging: add the go7007 video driver")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>