Fix a typo in the variable name. Only check path for a single library name.

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org> 

diff -Nur bctoolbox-0.4.0.orig/CMakeLists.txt bctoolbox-0.4.0/CMakeLists.txt
--- bctoolbox-0.4.0.orig/CMakeLists.txt	2016-10-06 17:30:41.000000000 +0200
+++ bctoolbox-0.4.0/CMakeLists.txt	2017-02-13 23:30:38.641288032 +0100
@@ -103,8 +103,8 @@
 endif()
 
 if(MBEDTLS_FOUND)
-	get_filename_component(mbedtls_library_path "${MBEDTLS_LIBRARIES}" PATH)
-	set(LIBS_PRIVATE "${LIBS_PRIVATE} -L${mbedlts_library_path}")
+	get_filename_component(mbedtls_library_path "${MBEDTLS_LIBRARY}" PATH)
+	set(LIBS_PRIVATE "${LIBS_PRIVATE} -L${mbedtls_library_path}")
 endif()
 if(POLARSSL_FOUND)
 	get_filename_component(polarssl_library_path "${POLARSSL_LIBRARIES}" PATH)