V4L/DVB (4731a): Kconfig: restore pvrusb2 menu items

Looks like the pvrusb2 menu items were accidentally removed in
git commit 1450e6be

This patch restores the menu items so that the pvrusb2 driver can be built.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>