drivers: dma_mcux_lpc: Change init level

Change init level of the mcux lpc dma driver to be
PRE_KERNEL_1 because some other hardware drivers
used on the same platforms as the lpc dma will be
dependent on the LPC DMA and are also initialized
in PRE_KERNEL_1, such as the Flexcomm UART driver
when using UART_ASYNC_API.

Therefore, remove k_malloc from init function and
make those variables statically defined instead of
heap allocated.

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