audit: Remove condition which always evaluates to false

After commit 3e1d0bb6 ("audit: Convert int limit
uses to u32"), by converting an int to u32, few conditions will always evaluate
to false.

These warnings were emitted during compilation:

kernel/audit.c: In function ‘audit_set_enabled’:
kernel/audit.c:347:2: warning: comparison of unsigned expression < 0 is always
false [-Wtype-limits]
  if (state < AUDIT_OFF || state > AUDIT_LOCKED)
	  ^
	  kernel/audit.c: In function ‘audit_receive_msg’:
	  kernel/audit.c:880:9: warning: comparison of unsigned expression < 0 is
	  always false [-Wtype-limits]
	      if (s.backlog_wait_time < 0 ||

The following patch removes those unnecessary conditions.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>