[ALSA] seq: reorganize sequencer client numbers

Modules: ALSA sequencer

Reduce the maximum possible number of global clients to 16 to make
more numbers available for card clients, and allow dynamically allocated
card client numbers to share the same range as application client
numbers to make sure that all 32 cards can be used at the same time.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>