ALSA: pcm: Fix unlocked state reads in read/write file ops

ALSA: pcm: Fix unlocked state reads in read/write file ops

The PCM read/write and readv/writev file operations reject streams in
OPEN or DISCONNECTED state before accessing the configured runtime
parameters. However, each operation reads runtime->state without the
PCM stream lock.

PCM state updates are serialized by the stream lock and may occur
concurrently from IRQ context. Use a local predicate based on
snd_pcm_get_state() to take a locked state snapshot for these VFS entry
checks.

This also consolidates the duplicated OPEN and DISCONNECTED tests. The
conditions and returned errors remain unchanged.

Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260610-alsa-pcm-read-write-state-helper-v1-1-93b7b992db09@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>