build: provide virtual self in kmods

build: provide virtual self in kmods

Add an implicit self-provide to kmods. apk can't handle self provides,
be it versioned or virtual, so opt for a prefix and a suffix instead.
Package name without a prefix/suffix is too generic and might conflict
with other packages, e.g. wireguard. This allows several variants to
provide the same virtual package without adding extra provides to the
default one, e.g. r8169 implicitly provides kmod-r8169-any and is marked
as default, so r8125 can explicitly provide @kmod-r8169-any as well.

Signed-off-by: George Sapkin <george@sapk.in>
Link: https://github.com/openwrt/openwrt/pull/21288
Signed-off-by: Robert Marko <robimarko@gmail.com>