BeaglePlay SBC[1] has Texas Instrument's WL18xx WiFi chipset[2].

Currently, WLAN_EN is configured as regulator and regulator-always-on.
However, the timing and wlan_en sequencing is not correctly modelled.

This causes the sdio access to fail during runtime-pm power operations
saving or during system suspend/resume/hibernation/freeze operations.
This is because the WLAN_EN line is not deasserted to low '0' to power
down the WiFi. So during restore, the WiFi driver tries to load the FW
without following correct power sequence. WLAN_EN => '1'/assert (high)
to power-up the chipset.

Use mmc-pwrseq-simple to drive TI's WiFi (WL18xx) chipset enable
'WLAN_EN'. mmc-pwrseq-simple provides power sequence flexibility with
support for post power-on and power-off delays.

Typical log signature that indicates this bug is:
wl1271_sdio mmc2:0001:2: sdio write failed (-110)

Followed by possibly a kernel warning (depending on firmware present):
WARNING: CPU: 1 PID: 45 at drivers/net/wireless/ti/wlcore/sdio.c:123 wl12xx_sdio_raw_write+0xe4/0x168 [wlcore_sdio]

[1] https://www.beagleboard.org/boards/beagleplay
[2] https://www.ti.com/lit/ds/symlink/wl1807mod.pdf

Fixes: f5a731f0 ("arm64: dts: ti: Add k3-am625-beagleplay")
Suggested-by: Shengyu Qu <wiagn233@outlook.com>
Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com>
Tested-by: Robert Nelson <robertcnelson@gmail.com>
Link: https://lore.kernel.org/r/20240325143511.2144768-1-nm@ti.comSigned-off-by: Nishanth Menon <nm@ti.com>