arm64: dts: freescale: ls1028a: Remove undocumented 'fsl,ls-pcie-ep'

Remove the undocumented compatible string 'fsl,ls-pcie-ep' property from
the ls1028a device tree source to fix DTB_CHECK warnings.

arch/arm64/boot/dts/freescale/fsl-ls1028a-rdb.dtb: pcie-ep@3400000: compatible: ['fsl,ls1028a-pcie-ep', 'fsl,ls-pcie-ep'] is too long
	from schema $id: http://devicetree.org/schemas/pci/fsl,layerscape-pcie-ep.yaml#Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi

@@ -674,7 +674,7 @@ pcie1: pcie@3400000 {
 		};
 
 		pcie_ep1: pcie-ep@3400000 {
-			compatible = "fsl,ls1028a-pcie-ep","fsl,ls-pcie-ep";
+			compatible = "fsl,ls1028a-pcie-ep";
 			reg = <0x00 0x03400000 0x0 0x00100000
 			       0x80 0x00000000 0x8 0x00000000>;
 			reg-names = "regs", "addr_space";
@@ -713,7 +713,7 @@ pcie2: pcie@3500000 {
 		};
 
 		pcie_ep2: pcie-ep@3500000 {
-			compatible = "fsl,ls1028a-pcie-ep","fsl,ls-pcie-ep";
+			compatible = "fsl,ls1028a-pcie-ep";
 			reg = <0x00 0x03500000 0x0 0x00100000
 			       0x88 0x00000000 0x8 0x00000000>;
 			reg-names = "regs", "addr_space";