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

include/linux/mfd/syscon.h

@@ -17,19 +17,16 @@
 struct device_node;
 
 #ifdef CONFIG_MFD_SYSCON
-extern struct regmap *device_node_to_regmap(struct device_node *np);
-extern struct regmap *syscon_node_to_regmap(struct device_node *np);
-extern struct regmap *syscon_regmap_lookup_by_compatible(const char *s);
-extern struct regmap *syscon_regmap_lookup_by_phandle(
-					struct device_node *np,
+struct regmap *device_node_to_regmap(struct device_node *np);
+struct regmap *syscon_node_to_regmap(struct device_node *np);
+struct regmap *syscon_regmap_lookup_by_compatible(const char *s);
+struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
 					       const char *property);
-extern struct regmap *syscon_regmap_lookup_by_phandle_args(
-					struct device_node *np,
+struct regmap *syscon_regmap_lookup_by_phandle_args(struct device_node *np,
 						    const char *property,
 						    int arg_count,
 						    unsigned int *out_args);
-extern struct regmap *syscon_regmap_lookup_by_phandle_optional(
-					struct device_node *np,
+struct regmap *syscon_regmap_lookup_by_phandle_optional(struct device_node *np,
 							const char *property);
 #else
 static inline struct regmap *device_node_to_regmap(struct device_node *np)