docker: add expansion for docker-test-FOO to Makefile.include

This allows us to run a particular test on all docker images. For
example:

  make docker-test-unit

Will run the unit tests on every supported image. At the same time
rename docker-test to docker-all-tests to be clearer.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

tests/docker/Makefile.include

@@ -148,7 +148,8 @@ $(foreach i,$(filter-out $(DOCKER_PARTIAL_IMAGES),$(DOCKER_IMAGES) $(DOCKER_DEPR
 		$(eval docker-$t@$i: docker-image-$i docker-run-$t@$i) \
 	) \
 	$(foreach t,$(DOCKER_TESTS), \
-		$(eval docker-test: docker-$t@$i) \
+		$(eval docker-all-tests: docker-$t@$i) \
+		$(eval docker-$t: docker-$t@$i) \
 	) \
 )
 
@@ -158,7 +159,8 @@ docker:
 	@echo 'Available targets:'
 	@echo
 	@echo '    docker:              Print this help.'
-	@echo '    docker-test:         Run all image/test combinations.'
+	@echo '    docker-all-tests:    Run all image/test combinations.'
+	@echo '    docker-TEST:         Run TEST on all image combinations.'
 	@echo '    docker-clean:        Kill and remove residual docker testing containers.'
 	@echo '    docker-TEST@IMAGE:   Run "TEST" in container "IMAGE".'
 	@echo '                         Note: "TEST" is one of the listed test name,'