r600/sfn: Initialize ShaderFromNir members in constructor.

Fix defect reported by Coverity Scan.

Uninitialized scalar field (UNINIT_CTOR)
uninit_member: Non-static class member chip_class is not initialized in
this constructor nor in any functions that it calls.
uninit_member: Non-static class member scratch_size is not initialized
in this constructor nor in any functions that it calls.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7648>

src/gallium/drivers/r600/sfn/sfn_nir.cpp

@@ -48,8 +48,10 @@ namespace r600 {
 using std::vector;
 
 ShaderFromNir::ShaderFromNir():sh(nullptr),
+   chip_class(CLASS_UNKNOWN),
    m_current_if_id(0),
-   m_current_loop_id(0)
+   m_current_loop_id(0),
+   scratch_size(0)
 {
 }