dma_mcux_lpc: Fix descriptor address conversion when used by DSP

The SDK FSL DMA driver converts descriptor addresses to DMA's address
space when linking descriptors. The Zephyr dma_mcux_lpc driver is
missing the inverse conversion when dereferencing the linked next
descriptor pointer.

This isn't a problem when this driver is used on the M33 core
of the MIMXRT595S because the M33 can access the address space
of the DMA (0x20000000+). But when the Fusion F1 DSP core uses
this driver, the DSP cannot access the DMA's address space
so the inverse conversion is needed.

Signed-off-by: Yicheng Li <yichengli@google.com>