Build: Remove Library Model branch in build system

Library Model is deprecated, so remove library model branch in build
system. TFM_PSA_API is defined as default and remove TFM_LIB_MODEL.

Signed-off-by: Summer Qin <summer.qin@arm.com>
Change-Id: I502f54b78d0c878356033efabed784e25284bc29
diff --git a/test/config/set_config.cmake b/test/config/set_config.cmake
index 367e306..c615725 100644
--- a/test/config/set_config.cmake
+++ b/test/config/set_config.cmake
@@ -107,12 +107,12 @@
 ########################## SLIH/FLIH IRQ Test ##################################
 
 # Make FLIH IRQ test as the default IRQ test
-if (NOT TFM_LIB_MODEL AND PLATFORM_FLIH_IRQ_TEST_SUPPORT
+if (PLATFORM_FLIH_IRQ_TEST_SUPPORT
     AND TEST_NS AND NOT TEST_NS_SLIH_IRQ)
     set(TEST_NS_FLIH_IRQ        ON        CACHE BOOL      "Whether to build NS regression First-Level Interrupt Handling tests")
 endif()
 
-if (NOT TFM_LIB_MODEL AND PLATFORM_SLIH_IRQ_TEST_SUPPORT
+if (PLATFORM_SLIH_IRQ_TEST_SUPPORT
     AND TEST_NS AND NOT TEST_NS_FLIH_IRQ)
     set(TEST_NS_SLIH_IRQ        ON        CACHE BOOL      "Whether to build NS regression Second-Level Interrupt Handling tests")
 endif()
@@ -136,11 +136,6 @@
     set(TEST_S_SFN_BACKEND      ON        CACHE BOOL      "Whether to build S regression SFN backend tests")
 endif()
 
-######################### Library Model Specific Tests #########################
-if (TFM_LIB_MODEL AND TEST_NS)
-    set(TEST_NS_CORE            ON        CACHE BOOL      "Whether to build NS regression Core tests")
-endif()
-
 ########################## Load default config #################################
 
 if (TEST_S)