README: Add section about releases
Makefile: Split videobuf-related stuff into videobuf.mk

Also makes the source directory or tarball optional.
Makefile: Clean videobuf-dma-sg.c as well
staging: Solo6x10: Changed solo6010* -> solo*, solo6x10* etc.

Signed-off-by: Krzysztof Hałasa <khalasa@piap.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Ismael Luceno <ismael.luceno@corp.bluecherry.net>
Merge branch 'master' into next