rockchip/vcodec: fix double lock and some warning

rockchip/vcodec: fix double lock and some warning

fix following problems:

vcodec_service.c:1613 try_set_reg()
error: double lock 'mutex:&pservice->shutdown_lock'
vcodec_service.c:1682 try_set_reg()
warn: inconsistent returns 'mutex:&pservice->shutdown_lock'.
  Locked on:   line 1614
  Unlocked on: line 1682

vcodec_service.c:599 vpu_get_clk()
warn: missing break? reassigning 'pservice->pd_video'
vcodec_service.c:901 vcodec_fd_to_iova()
warn: returning -1 instead of -ENOMEM is sloppy
vcodec_service.c:1100 vcodec_bufid_to_iova()
warn: returning -1 instead of -ENOMEM is sloppy
vcodec_service.c:1209 reg_init()
warn: passing __func__ while the format string already
contains the name of the function 'reg_init'
vcodec_service.c:1231 reg_init()
warn: passing __func__ while the format string already
contains the name of the function 'reg_init'
vcodec_service.c:1237 reg_init()
warn: passing __func__ while the format string already
contains the name of the function 'reg_init'
vcodec_service.c:1714 return_reg()
warn: passing __func__ while the format string already
contains the name of the function 'return_reg'

Change-Id: Ia2d3be7ad7a726d9af9e58c25079e6c11a7d302f
Signed-off-by: alpha lin <alpha.lin@rock-chips.com>