Kbuild.mk: remove all - they caused confusio many times

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
Makefile: remove unused code

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
do not build omaplfb.ko and bufferclass_ti.ko

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>