@martinayotte Thanks a lot, it worked.
For anyone else looking for solution; below file has to be changed; patch created and then image built (with patch placed in build\userpatches\kernel\sunxi-next)
build\cache\sources\linux-mainline\linux-4.14.y\arch\arm\boot\dts\sun7i-a20-bananapi.dts
&mmc0 {
pinctrl-names = "default";
pinctrl-0 = <&mmc0_pins_a>, <&mmc0_cd_pin_bananapi>;
vmmc-supply = <®_vcc3v3>;
bus-width = <4>;
broken-cd;
cd-inverted;
status = "okay";
};