* Clocks were wrongly configured - way too fast because there is no primary divider on LPC4330
This is fixed by means of changing the definitions in the board.h file. I've edited the one for the lpc4330-xplorer board because I'm actually working with Versiboard and don't want to contribute that config just yet while I've still got the drains up on it.
* The LPC43_SDMMC_DELAY register was not being set
I suspect, in the 'real world', it's possible to get away without setting this, but I've added a register definition, default value and register access macros into arch/arm/src/lpc43xx/chip/lpc43_scu.h and then used them in arch/arm/src/lpc43xx/lpc43_sdmmc.c.
* The LPC43_SDMMC_BLKSIZ and LPC43_SDMMC_BYTECNT registers had the wrong values.
The management have already implemented a rather nice block level interface for the stm32 so I've just re-used that to write to these registers as required. I'm slightly nervous that accessing the configuration registers (SCR being the prime example) which has a much smaller block size may not be being done in the right way but it does seem to work correctly, so let's assume it's all OK until someone tells me otherwise.
These fixes have been tested with DMA-based read/write on a LPC4330. Speed via nsh is pretty low but I'm assuming that's just a buffering/implementation issue for now.
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