bcm2835-bootloader: install and use start_x.elf and fixup_x.dat per default

Signed-off-by: Stephan Raue <stephan@openelec.tv>
projects/RPi/options: revert part of acdd4c8

Signed-off-by: Stephan Raue <stephan@openelec.tv>
Merge branch 'master' of github.com:OpenELEC/OpenELEC.tv