ARM: dts: exynos4210-universal_c210: Disable DMA for UARTs

PDMA for UART devices seems not to be working properly on Exynos 4210
revision 0 used in Universal C210 boards, so disable it to let one to
use UART devices (driver defaults to PIO mode if DMA is not present).

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>