riscv/qemu: add CMake for NuttSBI

This allows building NuttSBI based kernel image with CMake so that
to support out-of-tree building.

Signed-off-by: Yanfeng Liu <yfliu2008@qq.com>

boards/risc-v/qemu-rv/rv-virt/src/CMakeLists.txt

@@ -31,9 +31,11 @@ endif()
 target_sources(board PRIVATE ${SRCS})
 
 if(CONFIG_ARCH_CHIP_QEMU_RV)
-
   if(CONFIG_BUILD_KERNEL)
     set(LDFILE ld-kernel.script)
+    if(CONFIG_NUTTSBI)
+      set(LDFILE ld-nuttsbi.script)
+    endif()
   else()
     set(LDFILE ld.script)
   endif()