hwmon: (gpio-fan) Use is_visible to determine if attributes should be created
hwmon: (gpio-fan) Use is_visible to determine if attributes should be created

Simplify code and reduce object size by more than 300 bytes (x86_64).

Cc: Jamie Lentin <112f489f6b265cdf4e4892f7b952cd36fc0ecd5f@lentin.co.uk>
Cc: Simon Guinot <3ab4e30ada880520f74922b979fc5ca34d9375bb@sequanux.org>
Tested-by: Simon Guinot <3ab4e30ada880520f74922b979fc5ca34d9375bb@sequanux.org>
Signed-off-by: Guenter Roeck <ba324ca7b1c77fc20bb970d5aff6eea9377918a5@roeck-us.net>

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