power: vm-bms: Use "of_parse_phandle" to parse battery-data property

Currently "of_find_node_by_name" is used to parse battery-data property.
This is not the correct function to parse phandle. Fix it by replacing
it with "of_parse_phandle".

Change-Id: I18f827800f088d01b8edd0fcab3fea8405ad5a3f
Signed-off-by: Kavya Nunna <knunna@codeaurora.org>