hw/ppc/xive2_regs: Remove unnecessary 'cpu.h' inclusion

xive2_regs.h only requires declarations from "qemu/bswap.h".
Include it instead of the huge target-specific "cpu.h".

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Message-Id:  <20231122183920.17905-1-philmd@linaro.org>

include/hw/ppc/xive2_regs.h

@@ -10,7 +10,7 @@
 #ifndef PPC_XIVE2_REGS_H
 #define PPC_XIVE2_REGS_H
 
-#include "cpu.h"
+#include "qemu/bswap.h"
 
 /*
  * Thread Interrupt Management Area (TIMA)