bes2600: demote 'wait pm ind timeout' from bes_err to bes_devel

bes2600_pwr_enter_lp_mode() logs 'wait pm ind timeout' at bes_err
level every time wait_for_completion_timeout() on the firmware's
PM-change indication returns 0. The preceding patch ('bes2600:
gate device LP-mode entry on successful per-VIF firmware
handshake') already handles this case correctly: the per-VIF
timeouts counter is incremented, the function returns
-ETIMEDOUT, and the device-side LP transition is skipped -- the
cascade into sdio_tx_work splats and [RX] Receive failure
messages is prevented.

The timeout itself is benign steady-state noise on the PineTab2
(BES2600WM). Firmware occasionally misses the 5 s PM-change
deadline when mac80211 flips power-save rapidly during
association or roaming; observed rate on a quiet, associated
ohm is roughly 3-10 events per 10 min of uptime, with no
user-visible effect. Keeping it at bes_err() level (== KERN_ERR,
priority 3) floods dmesg with what is already a handled
condition and makes real SDIO / PM errors harder to spot.

Demote to bes_devel() (== KERN_DEBUG gated on the driver's debug
flag). The gate in the caller is unchanged, so the downstream
suppression behaviour introduced by the earlier patch remains.
Real pathologies -- bes_err("set operation mode fail") on the
same path, and the timeouts != 0 / -ETIMEDOUT return consumed
by callers -- still surface at bes_err() / return-value level.

Signed-off-by: Markus Fritsche <fritsche.markus@gmail.com>

bes2600/bes_pwr.c

@@ -538,7 +538,7 @@ static int bes2600_pwr_enter_lp_mode(struct bes2600_common *hw_priv)
 				atomic_set(&hw_priv->bes_power.pm_set_in_process, 0);
 				reinit_completion(&hw_priv->bes_power.pm_enter_cmpl);
 				if (!status) {
-					bes_err("%s, wait pm ind timeout\n", __func__);
+					bes_devel("%s, wait pm ind timeout\n", __func__);
 					timeouts++;
 				}
 			} else {