scripts/mkimag: use different name for uefi images
xf86-video-nvidia: update to xf86-video-nvidia-334.21
bcm2835-driver: update to bcm2835-driver-bec4bd0

Signed-off-by: Stephan Raue <stephan@openelec.tv>
bcm2835-bootloader: update to bcm2835-bootloader-bec4bd0

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