build: fix PYTHONPYCACHEPREFIX path

Type: make
Change-Id: I20fd245585e5b62ff20fe3adf20b14bfef47a9ca
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 32f0e7e..4be2473 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -71,7 +71,7 @@
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/${VPP_RUNTIME_DIR})
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/${VPP_LIBRARY_DIR})
 set(VPP_BINARY_DIR ${CMAKE_BINARY_DIR}/CMakeFiles)
-set(PYENV PYTHONPYCACHEPREFIX=${CMAKE_BINARY_DIR}/CMakeFile/__pycache__)
+set(PYENV PYTHONPYCACHEPREFIX=${CMAKE_BINARY_DIR}/CMakeFiles/__pycache__)
 
 if (CMAKE_BUILD_TYPE)
   add_compile_options(-g -Werror -Wall)