gpio: drop retval check enforcing from gpiochip_remove()

gpio: drop retval check enforcing from gpiochip_remove()

As we start to decomission the return value from gpiochip_remove()
the compilers emit warnings due to the function being tagged
__must_check. So drop this until we remove the return value
altogether.

Cc: Abdoulaye Berthe <[email protected]>
Suggested-by: Stephen Rothwell <[email protected]>
Signed-off-by: Linus Walleij <[email protected]>