Add "read_from_device_file" method
Add "read_from_device_file" method

Add a private "read_from_device_file" method to avoid repetition of code that
needs to read data from a named sysfs GPIO file.

Signed-off-by: Nick Stevens <75ef9faee755c70589550b513ad881e5a603182c@bitcurry.com>

nastevens/rust-sysfs-gpio,rust-embedded/rust-sysfs-gpio,marjakm/rust-sysfs-gpio,jwilm/rust-sysfs-gpio