validation: Test leon3_irqmap_get()

The validation test suite checked no LEON3 interrupt map function.

Add the test case which the specification of leon3_irqmap_get()
generates.  Build it in the BSP validation test suite of the GR712RC,
the GR740 and the GR765.

Assisted-by: Claude:claude-opus-5-5 claude-code
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>

spec/build/testsuites/validation/bsps/objsparcleon3irq.yml

@@ -0,0 +1,17 @@
+SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
+build-type: objects
+cflags: []
+copyrights:
+- Copyright (C) 2026 embedded brains GmbH & Co. KG
+cppflags: []
+cxxflags: []
+enabled-by:
+- sparc/gr712rc
+- sparc/gr740
+- sparc/gr765
+includes: []
+install: []
+links: []
+source:
+- testsuites/validation/bsps/tc-sparc-leon3-irqmap-get.c
+type: build

spec/build/testsuites/validation/bsps/validation-bsp-0.yml

@@ -23,6 +23,8 @@ links:
   uid: objsparcgr712rc
 - role: build-dependency
   uid: objsparcgr740
+- role: build-dependency
+  uid: objsparcleon3irq
 source:
 - testsuites/validation/bsps/ts-validation-bsp-0.c
 stlib: []