scylla_io_setup condition for nr_disks was using the bitwise operator
(&) instead of logical and operator (and) causing the io_properties
files to have incorrect values
Fixes#7341
Reviewed-by: Lubos Kosco <lubos@scylladb.com>
Signed-off-by: Shlomi Livne <shlomi@scylladb.com>
Closes#8019