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.
6ed875a63b