drm/i915: s/dpio_lock/sb_lock/

Rename dpio_lock to sb_lock to inform the reader that its primary
purpose is to protect the sideband mailbox rather than some DPIO
state.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --cc drivers/gpu/drm/i915/i915_dma.c
Simple merge

diff --cc drivers/gpu/drm/i915/i915_drv.h
Simple merge

diff --cc drivers/gpu/drm/i915/intel_display.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_dp.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_dsi.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_dsi_pll.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_hdmi.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_pm.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_sideband.c
Simple merge