xbmc: add PR4838

Signed-off-by: Stephan Raue <stephan@openelec.tv>
bcm2835-driver: update to bcm2835-driver-2990b78

Signed-off-by: Stephan Raue <stephan@openelec.tv>
bcm2835-bootloader: update to bcm2835-bootloader-2990b78

Signed-off-by: Stephan Raue <stephan@openelec.tv>