gpio: gpio-it87: Fix formatting issues which confuse kerneldoc

Kerneldoc expects struct properties to be documented using the syntax
'@.*: ', but no ':' has been provided in 'struct it87_gpio's
header. Add them to stop confusing kerneldoc.

Fixes the following W=1 warnings:

drivers/gpio/gpio-it87.c:69: warning: Function parameter or member 'chip' not described in 'it87_gpio'
drivers/gpio/gpio-it87.c:69: warning: Function parameter or member 'lock' not described in 'it87_gpio'
drivers/gpio/gpio-it87.c:69: warning: Function parameter or member 'io_base' not described in 'it87_gpio'
drivers/gpio/gpio-it87.c:69: warning: Function parameter or member 'io_size' not described in 'it87_gpio'
drivers/gpio/gpio-it87.c:69: warning: Function parameter or member 'output_base' not described in 'it87_gpio'
drivers/gpio/gpio-it87.c:69: warning: Function parameter or member 'simple_base' not described in 'it87_gpio'
drivers/gpio/gpio-it87.c:69: warning: Function parameter or member 'simple_size' not described in 'it87_gpio'

Signed-off-by: Lee Jones <[e-mail]>
Cc: "Diego Elio Pettenò" <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-it87.c

···
 
 /**
  * struct it87_gpio - it87-specific GPIO chip
- * @chip the underlying gpio_chip structure
- * @lock a lock to avoid races between operations
- * @io_base base address for gpio ports
- * @io_size size of the port rage starting from io_base.
- * @output_base Super I/O register address for Output Enable register
- * @simple_base Super I/O 'Simple I/O' Enable register
- * @simple_size Super IO 'Simple I/O' Enable register size; this is
+ * @chip: the underlying gpio_chip structure
+ * @lock: a lock to avoid races between operations
+ * @io_base: base address for gpio ports
+ * @io_size: size of the port rage starting from io_base.
+ * @output_base: Super I/O register address for Output Enable register
+ * @simple_base: Super I/O 'Simple I/O' Enable register
+ * @simple_size: Super IO 'Simple I/O' Enable register size; this is
  *	required because IT87xx chips might only provide Simple I/O
  *	switches on a subset of lines, whereas the others keep the
  *	same status all time.