
The variable name should have been named `kernel_cmdline_extra`, so
let's rename it to match the expectations of the rest of Mesa.
Fixes: 4362d5913f
("ci/b2c: import all variables starting with `B2C_`")
Signed-off-by: Martin Roukala (né Peres) <martin.roukala@mupuf.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26686>