sound: core: Remove redundant variable and return the last statement

Return the result from file->f_op->open() directly instead of
taking this in another redundant variable. Make the typical
return the last statement, return early and reduce the indentation
too.

Signed-off-by: Meng Tang <tangmeng@uniontech.com>
Link: https://lore.kernel.org/r/20220228050253.1649-2-tangmeng@uniontech.com


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