drivers: regulator: pfuze100: Defer probe on identify error

Sometimes the PFUZE100 doesn't respond over I2C.  We don't know why.

To work around this problem, return -EPROBE_DEFER instead of failing
outright.

Signed-off-by: Sean Cross <xobs@kosagi.com>
arch: arm: dts: Change Novena LED trigger to default-on

We want to have the least offensive LED trigger type set as the
default trigger.

Signed-off-by: Sean Cross <xobs@kosagi.com>
novena-defconfig: Add GPIO LED support

Signed-off-by: Sean Cross <xobs@kosagi.com>
drivers: regulator: Try harder to get PFUZE100 to respond

The PFUZE100 is critical to the system, as it controls USB voltage.  If
the chip doesn't respond, the system is useless.  Try up to five times to
talk to it.

Signed-off-by: Sean Cross <xobs@kosagi.com>
it6251: Attempt to make powerup more robust

We now check to see if video has stabilized during boot.  This is an
attempt to make the video more reliable.

Signed-off-by: Sean Cross <xobs@kosagi.com>
drivers: gpu: bridge: Fix IT6251 powerup

The IT6251 would have problems occasionally where it wouldn't sync, or
wouldn't initialize properly.

We solve this problem by moving initialization and link training to a
workqueue, so that it will calibrate as soon as the LCD display becomes
active again.

Signed-off-by: Sean Cross <xobs@kosagi.com>
drivers: regulator: pfuze100: Try multiple times to register

The PFUZE100 seems to go on holiday sometimes during boot.  This can
happen when querying it for its version information, or when registering
a regulator.

Trying multiple times works around the problem.

Signed-off-by: Sean Cross <xobs@kosagi.com>
drivers: gpu: it6251: Limit to twenty retries

Signed-off-by: Sean Cross <xobs@kosagi.com>