x86: edison: Mark eMMC non-removable

eMMC is non-removable on Intel Edison board. Fix the DTS accordingly.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/dts/edison.dts

@@ -88,6 +88,7 @@
 	emmc: mmc@ff3fc000 {
 		compatible = "intel,sdhci-tangier";
 		reg = <0xff3fc000 0x1000>;
+		non-removable;
 	};
 
 	sdcard: mmc@ff3fa000 {