One blinking mode is good enough, and two is too much. The best aproach
is emulate the fast blinking with the slow blinking, that it is more
used.
It is removed the flag ATTR_FASTBLINK because it has not a different
meaning of ATTR_BLINK, so it is not needed.
Signed-off-by: Roberto E. Vargas Caballero <k0ga@shike2.com>