regmap: fix bulk writes on paged registers

[ Upstream commit db057679de3e9e6a03c1bcd5aee09b0d25fd9f5b ]

On buses like SlimBus and SoundWire which does not support
gather_writes yet in regmap, A bulk write on paged register
would be silently ignored after programming page.
This is because local variable 'ret' value in regmap_raw_write_impl()
gets reset to 0 once page register is written successfully and the
code below checks for 'ret' value to be -ENOTSUPP before linearising
the write buffer to send to bus->write().

Fix this by resetting the 'ret' value to -ENOTSUPP in cases where
gather_writes() is not supported or single register write is
not possible.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/base/regmap/regmap.c

@@ -1618,6 +1618,8 @@ static int _regmap_raw_write_impl(struct regmap *map, unsigned int reg,
 					     map->format.reg_bytes +
 					     map->format.pad_bytes,
 					     val, val_len);
+	else
+		ret = -ENOTSUPP;
 
 	/* If that didn't work fall back on linearising by hand. */
 	if (ret == -ENOTSUPP) {