iwinfo: reorganize iwinfo header to enum and defines

iwinfo: reorganize iwinfo header to enum and defines

iwinfo.h have a mixed way to declare defines, some use enum, some define
bits in enum and other have their own special way. In all of this case
the count of all this defines is hardcoded to an arbitrary number.

To make code less error prone, convert everything to a common pattern
and use enum way to calculate the count of each flags.

Also drop defining number for each flag and just declare that the enum
starts from 0.

Move the related char array just below the define declaration to improve
code readability.

No functionl change intended.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>