V4L/DVB (7716): pvrusb2: clean up global functions

This patch contains the following cleanups:
- make the following needlessly global function static:
  - pvr2_hdw_set_cur_freq()
- #if 0 the following unused global functions:
  - pvr2_hdw_get_state_name()
  - pvr2_hdw_get_debug_info_unlocked()
  - pvr2_hdw_get_debug_info_locked()

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>