Fix i2c and spi to compile for Netduino Plus 2
Merge branch 'fix-netduino-i2c-spi' of github.com:dhylands/micropython into dhylands-fix-netduino-i2c-spi
stmhal: Improved configurability for I2C and SPI busses.

The HAL handles for the I2C/SPI objects are rather large, so we don't
want to unnecessarily include them.
Merge branch 'master' of github.com:micropython/micropython