[ARM] pxa/em-x270: remove duplicated #include

Remove duplicated #include in arch/arm/mach-pxa/em-x270.c.

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Acked-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: Eric Miao <eric.miao@marvell.com>