drivers: dma: extended dma_slot bitwidth from 7bits to 8-bits
drivers: dma: extended dma_slot bitwidth from 7bits to 8-bits

NXP i.MXRT11xx devices have up to 202 dma slots(peripheral dma requests).
Extended dma_slot to 8-bits to support more dma requests.

Signed-off-by: Chay Guo <88511207710d0999c7db4e6ca254ffdb3c9fc98f@nxp.com>

zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr