installer: add MMC support

Signed-off-by: Stephan Raue <stephan@openelec.tv>
projects/Generic/linux: buildin MMC to kernel

Signed-off-by: Stephan Raue <stephan@openelec.tv>
projects/Generic/options: install nvidia legacy driver on i386 builds, remove radeonsi driver from i386 builds, remove r200 driver on x86_64 builds

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