Delete unnecessary checks before some function calls

Fixed debug logging bug in per_get_few_bits.

The function "free" is documented in the way that no action shall occur for
a passed null pointer. It is therefore not needed that a function caller
repeats a corresponding check.
http://stackoverflow.com/questions/18775608/free-a-null-pointer-anyway-or-check-first

This issue was fixed by using the software "Coccinelle 1.0.4".
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>

The following functions return immediately if a null pointer was passed.
* asn1p_constraint_free
* asn1p_paramlist_free
* asn1p_ref_free
* asn1p_value_free
* asn1p_wsyntx_free

It is therefore not needed that a function caller repeats a corresponding check.

This issue was fixed by using the software "Coccinelle 1.0.4".
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>