Kernel: add packages for common USB DVB adapters

DVB drivers are intended to be used with tvheadend package and easily available Astrometa USB DVB/analog tuners. More adapters can be added in the future.
This allows users to record and stream TV programs from DVB networks to tvheadend clients.

Major changes:
- Add new kernel module category: Multimedia
- Moved video cameras from Video to Multimedia. Video menu will contain only output devices.
- Add packages for these kernel modules:
  - Multimedia support
  - DVB USB (installs dvb-core and dvb-usb-v2)
  - Realtek RTL28xxU, RTL2830, RTL2832
  - Rafael Micro R820T
  - Panasonic MN88472 (no firmware)
  - Panasonic MN88473 (no firmware)
  - Sony CXD2841ER

Minor changes:
- Added new kernel config lines for v5.15 and v6.1.
- Changed input devices modules loading order from aprox. 60-66 to 80-83.
- Removed some variables (not needed, unlikely to change).
- USB audio needed a dependecy on kmod-multimedia, when kmod-multimedia is also selected.

Signed-off-by: Marius Dinu <[email protected]>