Build: Unify build artefacts naming

In case of NO_SWAP upgrade strategy the build artefacts
get a postfix (_0 or _1) to indicate which memory slot are
they intended. This patch remove the _0 postfix (but _1 still
exists) to be the same name of artefacts regardless the build
config.

Change-Id: I3a71c1212bd2f4120930e2cf033596b02c83f193
Signed-off-by: Tamas Ban <tamas.ban@arm.com>
diff --git a/bl2/ext/mcuboot/MCUBoot.cmake b/bl2/ext/mcuboot/MCUBoot.cmake
index 7c2caba..c880f78 100644
--- a/bl2/ext/mcuboot/MCUBoot.cmake
+++ b/bl2/ext/mcuboot/MCUBoot.cmake
@@ -30,10 +30,10 @@
 	endif()
 
 	if (DEFINED _MY_PARAMS_POSTFIX)
-		if (${_MY_PARAMS_POSTFIX} STREQUAL "_0")
-			set(MY_POSTFIX "0")
-		else()
+		if (${_MY_PARAMS_POSTFIX} STREQUAL "_1")
 			set(MY_POSTFIX "1")
+		else()
+			message(FATAL_ERROR "Unknown artefacts postfix: ${_MY_PARAMS_POSTFIX}")
 		endif()
 	endif()