GPDMA driver for the LPC43xx.  The GPDMA block is basically the same as the LPC17xx.  Only the clock configuration is different and LPC43xx has four different DMA request sources, where LPC17xx has only two.

boardctl:  Add new command to start the NX server as a kernel thread.  Also refresh more configurations.

NX:  Remove configuration CONFIG_NX_NXSTART.  nx_start.c is now built unconditionally in multi-user mode.

Back out the last change.  I just noticed some complexities that need to be verified before this is released onto the world.