OvmfPkg/VirtNorFlashDxe: drop block I/O protocol implementation
    
    We never boot from NOR flash, and generally rely on the firmware volume
    PI protocols to expose the contents. So drop the block I/O protocol
    implementation from VirtNorFlashDxe.
    
    Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
    Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>