efi_loader: initialize root node first

With commit 16ad946f ("efi_loader: change setup sequence") the
detection of block device was moved to the start of the initialization
sequence. In the case of virtio devices two handles with the same device
path being created.

The root node handle should be created before anything else.

Reported-by: Ard Biesheuvel <ardb@kernel.org>
Fixes: 16ad946f ("efi_loader: change setup sequence")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>