gpiomon: fix parsing of custom output formats
gpiomon: fix parsing of custom output formats

The '%%e' string should be printed as '%e' - the same as for printf()
format specifiers - but gpiomon prints '%%e' in this case. Fix it.

Signed-off-by: Bartosz Golaszewski <108de5fbc428215dc26df4468b48691526611148@gmail.com>

brgl/libgpiod,brgl/libgpiod,brgl/libgpiod,brgl/libgpiod