dts: lpc dma: Use dma-channels prop correctly

Current erroneous usages of dma-channels prop by lpc-dma nodes:
* dma-channels devicetree property should describe the number of
  channels supported by the dma controller, not the number of channels
  in use.
* LPC55SXX and RTXXX SOCs should be setting dma channels prop at SOC
  level, not board level, since it is an SOC property, not a board
  property.
* lpc55s28 has 23 channels for dma0, not 20.
* lpc55s28 has 10 channels for dma1, not 0.
* lpc55s69 has 23 channels for dma0, not 20.
* rt5xx has 37 channels for dma1, not 0.
* rt6xx has 33 channels for dma0, not 20.
* rt6xx has 33 channels for dma1, not 0.

Fix all of these issues

Signed-off-by: Declan Snyder <declan.snyder@nxp.com>