virtio-mem: Correct format specifier mismatch for RISC-V

This likely affects other, less popular host architectures as well.
Less common host architectures under linux get QEMU_VMALLOC_ALIGN (from
which VIRTIO_MEM_MIN_BLOCK_SIZE is derived) define to a variable of
type uintptr, which isn't compatible with the format specifier used to
print a user message. Since this particular usage of the underlying data
seems unique to this file, the simple fix is to just cast
QEMU_VMALLOC_ALIGN to uint32_t, which corresponds to the format specifier
used.

Signed-off-by: Bruce Rogers <brogers@suse.com>
Message-Id: <20200730130519.168475-1-brogers@suse.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>

hw/virtio/virtio-mem.c

@@ -36,7 +36,7 @@
  * Use QEMU_VMALLOC_ALIGN, so no THP will have to be split when unplugging
  * memory (e.g., 2MB on x86_64).
  */
-#define VIRTIO_MEM_MIN_BLOCK_SIZE QEMU_VMALLOC_ALIGN
+#define VIRTIO_MEM_MIN_BLOCK_SIZE ((uint32_t)QEMU_VMALLOC_ALIGN)
 /*
  * Size the usable region bigger than the requested size if possible. Esp.
  * Linux guests will only add (aligned) memory blocks in case they fully