Build: Improve configuration of IRQ tests

Also PERIPH_ACCCESS tests. Update docs.

Change-Id: I61274f9a067a2de7d45ffebedb81dd06d999600d
Signed-off-by: Raef Coles <raef.coles@arm.com>
diff --git a/config/config_default.cmake b/config/config_default.cmake
index 31d1ad0..b5b32f5 100644
--- a/config/config_default.cmake
+++ b/config/config_default.cmake
@@ -107,6 +107,8 @@
 ################################## Tests #######################################
 
 set(TFM_INTERACTIVE_TEST                OFF         CACHE BOOL      "Enable interactive tests")
+set(TFM_IRQ_TEST                        OFF         CACHE BOOL      "Enable IRQ tests")
+set(TFM_PERIPH_ACCESS_TEST              OFF         CACHE BOOL      "Enable peripheral access tests")
 
 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")