imx93_a55: cleanup: Remove unnecessary lib files

With the transition to the native Zephyr drivers, the imx93_a55/lib/dai.c
and imx93_a55/lib/dma.c files become unnecessary. As such, remove
them in an attempt to clean up the src/platform/imx93_a55/ hierarchy.

Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>

Author: LaurentiuM1234