disk: part: Enable get_info pointer for CONFIG_SPL_FAT_SUPPORT

disk: part: Enable get_info pointer for CONFIG_SPL_FAT_SUPPORT

The patch "dm: part: Convert partition API use to linker lists"
(sha1: 96e5b03c8ab749b6547f6a3ceb4d4b9f274211aa) is adding new
dependency for enabling SPL_EXT_SUPPORT to be able to get
information about DOS partition.
get_info is also required for FAT support only which is used on Xilinx
Zynq boards.

Reported-by: Nathan Rossi <nathan@nathanrossi.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>