input/hog-lib: avoid scanning characteristics too early

input/hog-lib: avoid scanning characteristics too early

We need to have active connection to fully discover a HOG instance,
and in the chain

	bt_hog_new()->
		gatt_db_foreach_service()->
		foreach_hog_service()->
		hog_attach_instance()

we have not set up hog->attrib yet. So let's skip calling
foreach_hog_chrc() from hog_attach_instance(), especially since
we will be calling bt_hog_attach() pretty much immediately after
bt_hog_new(), and we will be discovering characteristics there anyway.

Signed-off-by: Anuj Jain <anuj01.jain@samsung.com>
Signed-off-by: Ayush Garg <ayush.garg@samsung.com>