ALSA: isa: Fix assignment in if condition

ISA ES1688 and WSS  driver code contains a few assignments in if
condition, which is a bad coding style that may confuse readers and
occasionally lead to bugs.

This patch is merely for coding-style fixes, no functional changes.

Link: https://lore.kernel.org/r/20210608140540.17885-15-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>