ARM: dts: renesas: ape6evm: Drop bogus "mtd-rom" compatible value

make dtbs_check:

    arch/arm/boot/dts/r8a73a4-ape6evm.dtb: flash@0: compatible: 'oneOf' conditional failed, one must be fixed:
	    ['cfi-flash', 'mtd-rom'] is too long
	    'cfi-flash' is not one of ['amd,s29gl01gp', 'amd,s29gl032a', 'amd,s29gl256n', 'amd,s29gl512n', 'arm,versatile-flash', 'arm,vexpress-flash', 'cortina,gemini-flash', 'cypress,hyperflash', 'ge,imp3a-firmware-mirror', 'ge,imp3a-paged-flash', 'gef,ppc9a-firmware-mirror', 'gef,ppc9a-paged-flash', 'gef,sbc310-firmware-mirror', 'gef,sbc310-paged-flash', 'gef,sbc610-firmware-mirror', 'gef,sbc610-paged-flash', 'intel,28f128j3', 'intel,dt28f160', 'intel,ixp4xx-flash', 'intel,JS28F128', 'intel,JS28F640', 'intel,PC28F640P30T85', 'numonyx,js28f00a', 'numonyx,js28f128', 'sst,sst39vf320', 'xlnx,xps-mch-emc-2.00.a']
	    'cfi-flash' is not one of ['cypress,cy7c1019dv33-10zsxi', 'arm,vexpress-psram']
	    'mtd-rom' is not one of ['cfi-flash', 'jedec-flash']
	    'mtd-ram' was expected
	    From schema: Documentation/devicetree/bindings/mtd/mtd-physmap.yaml
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/1c773aed6bd794cf36a9a787f77469eaa1359bef.1693481518.git.geert+renesas@glider.be

arch/arm/boot/dts/renesas/r8a73a4-ape6evm.dts

@@ -164,7 +164,7 @@ &cpu0 {
 
 &bsc {
 	flash@0 {
-		compatible = "cfi-flash", "mtd-rom";
+		compatible = "cfi-flash";
 		reg = <0x0 0x08000000>;
 		bank-width = <2>;