buildroot

luarocks-package: lowercase the upstream name for LuaRocks

LuaRocks has a policy that the rockspec and rock filenames are lower
case. However, the upstream name may contain uppercase characters.
We have several packages like that in Buildroot. To simplify the
package .mk files, apply the lowercase from within the infra.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>