tc/m_gact: Drop dead code

tc/m_gact: Drop dead code

The use of 'ok' variable in parse_gact() is ineffective: The second
conditional increments it either if *argv is 'gact' or if
parse_action_control() doesn't fail (in which case exit() is called).
So this is effectively an unconditional increment and since no decrement
happens anywhere, all remaining checks for 'ok != 0' can be dropped.

Signed-off-by: Phil Sutter <phil@nwl.cc>