Fix the breakage due to upstream IREE change

build_iree failed due to renaming in
https://github.com/openxla/iree/pull/12687.

This CL fixes it.

Change-Id: Iaabbd56edb9363021c7537ee1bbff25a9793a163

cmake/riscv_iree.cmake

diff --git a/cmake/riscv_iree.cmake b/cmake/riscv_iree.cmake
index 3f36c03..0106b8e 100644
--- a/cmake/riscv_iree.cmake
+++ b/cmake/riscv_iree.cmake
@@ -10,7 +10,7 @@
 endif(RISCV_TOOLCHAIN_INCLUDED)
 set(RISCV_TOOLCHAIN_INCLUDED true)
 
-set(CMAKE_SYSTEM_PROCESSOR riscv)
+set(CMAKE_SYSTEM_PROCESSOR riscv32)
 set(CMAKE_CROSSCOMPILING ON CACHE BOOL "")
 
 if(CMAKE_HOST_SYSTEM_NAME STREQUAL Linux)