bsps/or1k/generic_or1k: Fix the include guard

The bsp.h and bsp/generic_or1k.h headers both used
LIBBSP_GENERIC_OR1K_H, so whichever was included first suppressed the
other.  Since bsp.h includes bsp/generic_or1k.h, every file which
included bsp.h first saw none of the register definitions.

Use the LIBBSP_<arch>_<bsp>_BSP_H form of the other BSPs for bsp.h and
leave the register header with the name it owns.

Update #5687.

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

bsps/or1k/generic_or1k/include/bsp.h

@@ -33,8 +33,8 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef LIBBSP_GENERIC_OR1K_H
-#define LIBBSP_GENERIC_OR1K_H
+#ifndef LIBBSP_OR1K_GENERIC_OR1K_BSP_H
+#define LIBBSP_OR1K_GENERIC_OR1K_BSP_H
 
 /**
  * @addtogroup RTEMSBSPsOR1K
@@ -60,5 +60,5 @@ extern "C" {
 
 /** @} */
 
-#endif /* LIBBSP_GENERIC_OR1K_H */
+#endif /* LIBBSP_OR1K_GENERIC_OR1K_BSP_H */