treewide: make use of PTR_ERR_OR_ZERO ...

PTR_ERR_OR_ZERO is designed to replace boiler plate like:

	if (IS_ERR(x))
		return PTR_ERR(x);
	return 0;

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: rave-sp-wdt: Explicitly access EEPROM for bootsource ...

RAVE SP firmware versions found on RDU2 provide decicated bootsource
manipulation commands, which, under the hood, are just thin wrappers
around write/read to a particular location in EEPROM.

Unfortunately, RAVE SP firmware found on RDU1, does not provide any
dedicated bootsource commands and its users are expected to access
EEPROM directly.

In order to avoid having separate code paths for handling those two
cases, convert the code to access EEPROM directly via NVMEM API.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: rave-sp-wdt: Remove bogus leftover code ...

This code should've been removed when the driver was rebased against
latest watchdog plumbing in Barebox.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: Port RAVE SP watchdog driver from Linux kernel ...

Port RAVE SP watchdog driver from Linux kernel

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>