nv50/ir: Initialize DataArray members in constructor.

nv50/ir: Initialize DataArray members in constructor.

Fix defects reported by Coverity Scan.

uninit_member: Non-static class member array is not initialized in this constructor nor in any functions that it calls.
uninit_member: Non-static class member arrayIdx is not initialized in this constructor nor in any functions that it calls.
uninit_member: Non-static class member baseAddr is not initialized in this constructor nor in any functions that it calls.
uninit_member: Non-static class member arrayLen is not initialized in this constructor nor in any functions that it calls.
uninit_member: Non-static class member baseSym is not initialized in this constructor nor in any functions that it calls.
uninit_member: Non-static class member vecDim is not initialized in this constructor nor in any functions that it calls.
uninit_member: Non-static class member eltSize is not initialized in this constructor nor in any functions that it calls.
uninit_member: Non-static class member file is not initialized in this constructor nor in any functions that it calls.
uninit_member: Non-static class member regOnly 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/7764>