sys/vfs/hammer: Change hkprintf() to macro and add variants [1/2]

sys/vfs/hammer: Change hkprintf() to macro and add variants [1/2]

This commit does the following.

1. Remove an inline function hkprintf().
2. Add a macro version of hkprintf() and its variants that
   embed the following prefix.
   "HAMMER: ..."
   "HAMMER(label) ..."
3. Replace raw kprintf() calls that have above prefix with
   newly added macros.

hkprintf() macro doesn't use hammer_debug_debug flag that was
used by the inline function version of hkprintf(), but this
doesn't make much difference from the way hkprintf() and
hammer_debug_debug have been used.