test/subsys/jwt: Work around for qemu_rx support

The qemu_rx some how with too big offset in "mov" instruction
cannot manipulate the memory correctly
This commit reconfigure the slot count to reduce the size of
psa_global_data_t struct so that issue on qemu_rx not occur

Signed-off-by: Duy Nguyen <duy.nguyen.xa@renesas.com>

Author: duynguyenxa

tests/subsys/jwt/prj.conf

@@ -9,3 +9,6 @@ CONFIG_ENTROPY_GENERATOR=y
 CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR=y
 
 CONFIG_REQUIRES_FULL_LIBC=y
+
+# Work around for qemu_rx
+CONFIG_MBEDTLS_PSA_KEY_SLOT_COUNT=1