gpiolib: let gpiochip_add_pin_range() specify offset

Like with commit 3c739ad0df
it is not always enough to specify all the pins of a gpio_chip
from offset zero to be added to a pin map range, since the
mapping from GPIO to pin controller may not be linear at all,
but need to be broken into a few consecutive sub-ranges or
1-pin entries for complicated cases. The ranges may also be
sparse.

This alters the signature of the function to accept offsets
into both the GPIO-chip local pinspace and the pin controller
local pinspace.

Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

include/linux/gpio.h

@@ -233,7 +233,8 @@ static inline int irq_to_gpio(unsigned irq)
 
 static inline int
 gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
-		       unsigned int pin_base, unsigned int npins)
+		       unsigned int offset, unsigned int pin_base,
+		       unsigned int npins)
 {
 	WARN_ON(1);
 	return -EINVAL;