Renamed dm "drivers" subcommand to "compat" (as it listed
compatibility strings) and prevent it from segfaulting when
drivers have no of_match populated.

Added a new "drivers" subcommand to dump a list of all known DM
drivers and for each, their uclass id, uclass driver and names of
attached devices.

Added a new "static" subcommand to dump a list of DM drivers with
statically defined platform data.

Signed-off-by: Niel Fourie <lusus@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>