staging:iio:magnetometer:ak8975: Don't assume 0 is an invalid GPIO
staging:iio:magnetometer:ak8975: Don't assume 0 is an invalid GPIO

gpio_is_valid() is the defined mechanism to determine whether a GPIO is
valid. Use this instead of assuming that 0 is an invalid GPIO.

Signed-off-by: Stephen Warren <5ef2a23ba3aff51d1cfc8c113c1ec34b608b3b13@nvidia.com>
Acked-by: Andrew Chew <9a53fa2b78b94926e01049233331b35b21a18d99@nvidia.com>
Signed-off-by: Jonathan Cameron <09f65b71b7655725897b2fd41a09a0cefe2e1ace@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@suse.de>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs