F4 fastram fix

The root cause of #855 was a combination of things:
* the trampoline buffers weren't being used on F4 due to a mismatch between macros.  PIOS_INCLUDE_FASTHEAP (correct) and PIOS_INCLUDE_FASTRAM (wrong).  The uavobjmgr wasn't ever compiling in the FASTHEAP code path which included the trampolines.
* the trampoline buffers also weren't forcing 4-byte alignment which is required on F4.
* the code path for the trampolines had typos in it so it wouldn't have compiled anyway.
* the stabilizationsettings uavo is the only settings UAVO that is actually larger than the threshold whereby the SPI driver will use DMA.

I've tested this on quanton.  This needs testing on F3/F1 targets before merging.