mfd: syscon: Remove extern from function prototypes

The kernel coding style does not require 'extern' in function prototypes
in .h files, so remove them as they are not needed.

To avoid checkpatch warnings such as
CHECK: Lines should not end with a '('
+struct regmap *syscon_regmap_lookup_by_phandle(

The indentation is also updated. No functional changes in this patch.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Link: https://lore.kernel.org/r/20240220115012.471689-3-peter.griffin@linaro.org


Signed-off-by: Lee Jones <lee@kernel.org>