drm/format-helper: Support multiple target formats results

In order to support multiple destination format conversions, store the
destination pitch and the expected result in its own structure.

Tested-by: Tales L. Aparecida <tales.aparecida@gmail.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220726230916.390575-4-jose.exposito89@gmail.com