dts: arm: nxp: lpc55s6x: add DMA channels at SOC level

Add DMA channels at SOC level for the LPC55S6x series SOCs, as the dma
requests are SOC specific properties and do not need to be modified at
the board level. Remove any DMA request definitions present at the board
level for the LPC55S69 evaluation board.

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>