nvc0/ir: Initialize SchedDataCalculator members in constructor.

nvc0/ir: Initialize SchedDataCalculator members in constructor.

Fix defects reported by Coverity Scan.

uninit_member: Non-static class member score is not initialized in this constructor nor in any functions that it calls.
uninit_member: Non-static class member prevData is not initialized in this constructor nor in any functions that it calls.
uninit_member: Non-static class member prevOp is not initialized in this constructor nor in any functions that it calls.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8604>