linux-dreambox: reduce size of dm500hd/dm800se kernels

hopefully with these changes we just get under the
magical size limit again, so the secondstage loader
can boot them.
linux-etxx00: dvb-usb-rtl28xxu update

patches prepared by Gennar1

-update the dvb-usb-rtl28xxu kernel driver to the latest
version (retrieved from the media_build tree).

-add support for the new r820t tuner that is used by several
cheap USB tuners (rtl2832+r820t).

Since the out-of-kernel Realtek driver dvb-usb-rtl2832 is
currently broken, this will allow users to switch to the
new in-kernel driver.

-rescale the SNR values in the range 0-0xffff (as we did with several other tuners).
linux-etxx00: remove dvb-usb-a867.patch

the a867 is now supported by the af9035 driver
Merge remote-tracking branch 'openpli3/master' into HEAD