The olimex-efm32g880f128-stk now defaults to use LEUART1 as the serial console.  Also fixes lots of compile bugs from the original LEUART checkin

This renames the stm32 spi frame format definition to the short description
name as well as the other cr2 register flags.

Note! STM32_SPI3_FRF was never used by nuttx somewhere

Signed-off-by: Marco Krahl <ocram.lhark@gmail.com>