mfd: 88pm860x: Remove unused extern declarations

commit 260a127b ("mfd: 88pm860x-i2c: Purge unused functions")
left behind this.
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20230728132841.10648-1-yuehaibing@huawei.comSigned-off-by: Lee Jones <lee@kernel.org>

include/linux/mfd/88pm860x.h

@@ -472,13 +472,7 @@ extern int pm860x_bulk_read(struct i2c_client *, int, int, unsigned char *);
 extern int pm860x_bulk_write(struct i2c_client *, int, int, unsigned char *);
 extern int pm860x_set_bits(struct i2c_client *, int, unsigned char,
 			   unsigned char);
-extern int pm860x_page_reg_read(struct i2c_client *, int);
 extern int pm860x_page_reg_write(struct i2c_client *, int, unsigned char);
 extern int pm860x_page_bulk_read(struct i2c_client *, int, int,
 				 unsigned char *);
-extern int pm860x_page_bulk_write(struct i2c_client *, int, int,
-				  unsigned char *);
-extern int pm860x_page_set_bits(struct i2c_client *, int, unsigned char,
-				unsigned char);
-
 #endif /* __LINUX_MFD_88PM860X_H */