Access to peripheral function port assignments

[pabigot]

When using SPI with a logic analyzer it's nice to enable a pullup/pulldown on SCLK so the initial state is what the analyzer expects. Need a way to get the port and pin for a specific function like SCLK given the peripheral handle like BSP430_USCI5_B0.

Also consider enabling all peripheral HPLs by default instead of having to request them; since they're pointers to register maps there should be no impact other than the size of the functions that translate between peripheral handles and hpl handles, and those should be inlined or called rarely.