drm/imx/dcss: have all init functions use devres

dcss currently allocates and ioremaps quite a few resources in its probe
function's call graph. Devres now provides convenient functions which
perform the same task but do the cleanup automatically.

Port all memory allocations and ioremap() calls to the devres
counterparts.

Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Reviewed-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Signed-off-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240124111904.18261-4-pstanner@redhat.com