setting HAL_USE_CAN uses the ChibiOS CAN driver instead of the AP_HAL
CAN driver. This is only used on the f103-periph as it significantly
reduces the size of the bootloader, which allows for f103 builds to
fit in the limited flash
on all other builds we are much better off using the HAL CAN driver as
it is much faster
This reverts commit 5de6c690d8.
That commit broke the build for the affected board as the chibios
headers rely on the name of the file matching a ifdef