When booting the HassOS VMDK appliance disk image on QEMU with OVMF UEFI
firmware, barebox numbers devices differently from other environments.
This patch makes the barebox `sh` implementation expand a pathname
wildcard at runtime, so that assigned disk indices != 0 will also work.
This fix introduces a potential (but most likely irrelevant)
bug/problem: If there is more than one disk connected to the system with
a matching name assigned, the wildcard will expand to two or more
pathnames, breaking the resulting `mount` command.
