drm/i915: Use REG_BIT for PLANE_WM bits

A couple of PLANE_WM bits were still using the hand
rolled (1<<N) form. Replace with REG_BIT().

v2: Rebase
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240513165945.15285-1-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/display/skl_universal_plane_regs.h

@@ -307,8 +307,8 @@
 #define _PLANE_WM_2(pipe)		_PIPE(pipe, _PLANE_WM_2_A_0, _PLANE_WM_2_B_0)
 #define _PLANE_WM_BASE(pipe, plane)	_PLANE(plane, _PLANE_WM_1(pipe), _PLANE_WM_2(pipe))
 #define PLANE_WM(pipe, plane, level)	_MMIO(_PLANE_WM_BASE(pipe, plane) + ((4) * (level)))
-#define   PLANE_WM_EN				(1 << 31)
-#define   PLANE_WM_IGNORE_LINES			(1 << 30)
+#define   PLANE_WM_EN				REG_BIT(31)
+#define   PLANE_WM_IGNORE_LINES			REG_BIT(30)
 #define   PLANE_WM_LINES_MASK			REG_GENMASK(26, 14)
 #define   PLANE_WM_BLOCKS_MASK			REG_GENMASK(11, 0)