Fixed compatibility with latest libopencm3

u{8,16,32} is no longer typedefed, so has been substituted for uint{8,16,32}_t
flash_program_byte no longer needs the FLASH_CR_PROGRAM_X8 argument
ADC_SMPR1_SMP_1DOT5CYC has been renamed to ADC_SMPR_SMP_3CYC
ADC_SMPR1_SMP_7DOT5CYC has been renamed to ADC_SMPR_SMP_15CYC
usbd_init now requires a control buffer, which we don't use
Merge pull request #1 from AWhetter/new-libopencm3

Fixed compatibility with latest libopencm3