ARM: dts: imx53-evk: Remove board support

imx53-evk board is discontinued by Freescale. The replacement is
imx53-qsb. Additionally this board is not supported by anyone and
in their current state is non-functional, for example PMIC not have
an IRQ line defined, so it is not works. This patch removes this DTS.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>