modpybhspi now does the needed multiplexing, calling out to modpybspi
(bitbanging SPI) for suitable peripheral ID's. modmachinespi (previous
multiplexer class) thus not needed and removed.

modpybhspi also updated to following standard SPI peripheral naming:
SPI0 is used for FlashROM and thus not supported so far. SPI1 is available
for users, and thus needs to be instantiated as:

spi = machine.SPI(1, ...)