staging: greybus: Inline gpio_chip_to_gb_gpio_controller()

staging: greybus: Inline gpio_chip_to_gb_gpio_controller()

Convert 'gpio_chip_to_gb_gpio_controller' from a macro to a static
inline function, to make the relevant types apparent in the
definition and to benefit from the type checking performed by
the compiler at call sites.

Signed-off-by: Sumitra Sharma <sumitraartsy@gmail.com>
Link: https://lore.kernel.org/r/3fc5d84a99574ac4a76d26427ac544de375adeb4.1679732179.git.sumitraartsy@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>