crypto-client: allow debug build of libraries and test binaries

Add DEBUG=1 in test_psasim() to helpers and final make to build
the libraries and the final binaries with debug symbols
enabled.

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/tests/psa-client-server/psasim/Makefile b/tests/psa-client-server/psasim/Makefile
index 583f1b9..01e3486 100644
--- a/tests/psa-client-server/psasim/Makefile
+++ b/tests/psa-client-server/psasim/Makefile
@@ -1,7 +1,7 @@
 CFLAGS += -Wall -Werror -std=c99 -D_XOPEN_SOURCE=1 -D_POSIX_C_SOURCE=200809L
 
 ifeq ($(DEBUG),1)
-	CFLAGS += -DDEBUG
+CFLAGS += -DDEBUG -O0 -g
 endif
 
 LIBPSACLIENT := -Llibpsaclient/ -lmbedcrypto -lmbedx509 -lmbedtls