nouveau/gsp: add kconfig option to enable GSP paths by default

Turing and Ampere will continue to use the old paths by default,
but we should allow distros to decide what the policy is.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240214040632.661069-1-airlied@gmail.com