Build: Enable PS NV counter test by default

This patch enables the PS NV counter tests by default.
But there is no effect of it when regression tests are disabled.

Documentation of it is updated as well.

Change-Id: Ibbce9da66f0242135ba71f8b8e9f0225823ca66f
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
diff --git a/config/config_default.cmake b/config/config_default.cmake
index dc7ab25..8793177 100644
--- a/config/config_default.cmake
+++ b/config/config_default.cmake
@@ -122,7 +122,7 @@
 set(TFM_IRQ_TEST                        OFF         CACHE BOOL      "Enable IRQ tests")
 set(TFM_PERIPH_ACCESS_TEST              OFF         CACHE BOOL      "Enable peripheral access tests")
 
-set(PS_TEST_NV_COUNTERS                 OFF         CACHE BOOL      "Use the test NV counters to test Protected Storage rollback scenarios")
+set(PS_TEST_NV_COUNTERS                 ON          CACHE BOOL      "Use the test NV counters to test Protected Storage rollback scenarios")
 
 set(TFM_CRYPTO_TEST_ALG_CBC             ON          CACHE BOOL      "Test CBC cryptography mode")
 set(TFM_CRYPTO_TEST_ALG_CCM             ON          CACHE BOOL      "Test CCM cryptography mode")