libxc: use xc_dom_panic when decompressor is not supported

libxc: use xc_dom_panic when decompressor is not supported

State explicitly that specific decompressor is not supported by libxc.
Without this change, libxc error message only says the provided kernel
is invalid, which is misleading.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: svenvan.van@gmail.com
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>