This change three things: (1) It adds HWFEAT_LSBFIRST as a new H/W feature. (2) It changes the implementations of SPI_SETBITS in the STM32 and EFM32 derivers so that negated bit numbers are simply errors and it adds the SPI_HWFEATURES method that can set the LSB bit order, and (3) It changes all calls with negative number of bits from all drivers: The number of bits is now always positive and SPI_HWFEATUREs is called with HWFEAT_LSBFIRST to set the bit order.