hw/usb: Use __attribute__((packed)) vs __packed

__packed is non standard and is not present in clang-cl.
__attribute__((packed)) has the same semantics.

Signed-off-by: Erwin Jansen <jansene@google.com>
Signed-off-by: Roque Arcudia Hernandez <roqueh@google.com>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20241101211720.3354111-1-roqueh@google.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

include/hw/usb/dwc2-regs.h

@@ -838,7 +838,7 @@
 struct dwc2_dma_desc {
         uint32_t status;
         uint32_t buf;
-} __packed;
+} QEMU_PACKED;
 
 /* Host Mode DMA descriptor status quadlet */