Leverage the LPC54xx back to the LPC43xx (where it came from originally)

Squashed commit of the following:

    arch/arm/src/lpc43xx:  SDMMC driver now builds for the LPC43 (provided that the proper definitions appear in the board.h file).
    arch/arm/src/lpc43xx:  Update basic changes to the ported lpc54xx driver for lpc43xx clocking and GPIOs.
    arch/arm/src/lpc43xx:  Brings in the LPC54xx SD/MMC driver with absolutely no changes other than changing all occurences of 54 to 43.
    arm/arm/src/lpc43xx:  Add build support for the lpc54 SDMMC driver.
    lpc54 SDMMC:  Check for successful data transfer last.  Checking first means that we miss errors.