layerscape: fix VFIO driver build issue since linux-4.14.99

layerscape: fix VFIO driver build issue since linux-4.14.99

The linux-4.14.99 had introduced below upstream patch.
6636dc5e01c6 arm64: io: Ensure value passed to __iormb() is held in a 64-bit register

It was causing VFIO driver build issue. This patch is to fix it.

 CC      drivers/vfio/fsl-mc/vfio_fsl_mc.o
In file included from ./include/linux/scatterlist.h:9:0,
                 from ./include/linux/iommu.h:22,
                 from drivers/vfio/fsl-mc/vfio_fsl_mc.c:14:
drivers/vfio/fsl-mc/vfio_fsl_mc.c: In function 'vfio_fsl_mc_dprc_wait_for_response':
./arch/arm64/include/asm/io.h:122:45: error: expected expression before ')' token
        : "=r" (tmp) : "r" ((unsigned long)(v))  \
                                             ^
drivers/vfio/fsl-mc/vfio_fsl_mc.c:334:3: note: in expansion of macro '__iormb'
   __iormb();
   ^~~~~~~
./arch/arm64/include/asm/io.h:122:45: error: expected expression before ')' token
        : "=r" (tmp) : "r" ((unsigned long)(v))  \
                                             ^
drivers/vfio/fsl-mc/vfio_fsl_mc.c:336:3: note: in expansion of macro '__iormb'
   __iormb();
   ^~~~~~~

Reported-by: Mathew McBride <matt@traverse.com.au>
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>