stmhal: Include fatfs headers using lib/fatfs prefix.

stmhal/Makefile

stmhal/diskio.c

stmhal/ffconf.c

stmhal/file.c

stmhal/fsusermount.c

stmhal/import.c

stmhal/lexerfatfs.c

stmhal/main.c

stmhal/modpyb.c

stmhal/moduos.c

stmhal/usbd_msc_storage.c