tools: ynl: lift an assumption about spec file name

tools: ynl: lift an assumption about spec file name

Currently the parsing code generator assumes that the yaml
specification file name and the main 'name' attribute carried
inside correspond, that is the field is the c-name representation
of the file basename.

The above assumption held true within the current tree, but will be
hopefully broken soon by the upcoming net shaper specification.
Additionally, it makes the field 'name' itself useless.

Lift the assumption, always computing the generated include file
name from the generated c file name.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Link: https://patch.msgid.link/24da5a3596d814beeb12bd7139a6b4f89756cc19.1724165948.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>