gpiolib: Discourage to use formatting strings in line names

Currently the documentation for line names allows to use %u inside
the alternative name. This is broken in character device approach
from day 1 and being in use solely in sysfs.

Character device interface has a line number as a part of its address,
so the users better rely on it. Hence remove the misleading documentation.

On top of that, there are no in-kernel users (out of 6, if I'm correct)
for such names and moreover if one exists it won't help in distinguishing
lines with the same naming as '%u' will also be in them and we will get
a warning in gpiochip_set_desc_names() for such cases.

Signed-off-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Reviewed-by: Kent Gibson <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bartosz Golaszewski <[e-mail]>

include/linux/gpio/driver.h

···
  * @names: if set, must be an array of strings to use as alternative
  *      names for the GPIOs in this chip. Any entry in the array
  *      may be NULL if there is no alias for the GPIO, however the
- *      array must be @ngpio entries long.  A name can include a single printk
- *      format specifier for an unsigned int.  It is substituted by the actual
- *      number of the gpio.
+ *      array must be @ngpio entries long.
  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  *	must while accessing GPIO expander chips over I2C or SPI. This
  *	implies that if the chip supports IRQs, these IRQs need to be threaded