[dts] [PATCH V2] tests/external_memory:VFIO module parameter increase the allowed limit

[Tu, Lijuan]

> According to commit 016763c21958 ("vfio: do not merge contiguous areas").
> VFIO module parameter ``dma_entry_limit`` with a default value of 64K.
> When application is out of DMA entries, these limits need to be adjusted to
> increase the allowed limit .
> 
> Signed-off-by: Chen Lingli <linglix.chen at intel.com>
> ---
> V2:modifie comment use git commit description style V1:modifie dts

Applied, thanks