ARM: dts: armada-38x: use regulator-boot-on for SATA regulators on Armada 388 GP

ARM: dts: armada-38x: use regulator-boot-on for SATA regulators on Armada 388 GP

Really, what we meant by regulator-always-on is that the regulators
are already turned on by the bootloader, for which regulator-boot-on
is a better description.

A net advantage of using regulator-boot-on is that the regulator is
not touched at boot time by the kernel, which avoids having the hard
drives spinning down and then up again, taking several (~5) seconds of
additional boot time.

In addition, there is no need to have such properties on the child
regulators used for SATA. Having it on the parent regulator that
really controls the GPIO is sufficient.

Without the patch:

[    3.945866] ata2: SATA link down (SStatus 0 SControl 300)
[    3.995862] ata3: SATA link down (SStatus 0 SControl 300)
[    4.005863] ata4: SATA link down (SStatus 0 SControl 300)
[    9.125861] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[    9.144575] ata1.00: ATA-8: WDC WD5003ABYX-01WERA1, 01.01S02, max UDMA/133
[    9.151471] ata1.00: 976773168 sectors, multi 0: LBA48 NCQ (depth 31/32)

 (and you can hear the disk spinning down and up during this 5.1
 seconds delay)

With the patch:

[    3.945988] ata2: SATA link down (SStatus 0 SControl 300)
[    4.005980] ata4: SATA link down (SStatus 0 SControl 300)
[    4.011404] ata3: SATA link down (SStatus 0 SControl 300)
[    4.145978] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[    4.153701] ata1.00: ATA-8: WDC WD5003ABYX-01WERA1, 01.01S02, max UDMA/133
[    4.160597] ata1.00: 976773168 sectors, multi 0: LBA48 NCQ (depth 31/32)

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>