CONFIG_DRM_RCAR_VSP is related to R-Car and not related to RZ/G2L
specific. This caused the below build issue. Fix this errors by replacing
CONFIG_DRM_RCAR_VSP->CONFIG_VIDEO_RENESAS_VSP1. While at it, use
IS_ENABLED() macro.

drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c:47:6: error: redefinition of 'rzg2l_du_vsp_enable'
   47 | void rzg2l_du_vsp_enable(struct rzg2l_du_crtc *crtc)
      |      ^~~~~~~~~~~~~~~~~~~
In file included from drivers/gpu/drm/renesas/rz-du/rzg2l_du_drv.h:18,
                 from drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c:30:
drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.h:72:20: note: previous definition of 'rzg2l_du_vsp_enable' with type 'void(struct rzg2l_du_crtc *)'
   72 | static inline void rzg2l_du_vsp_enable(struct rzg2l_du_crtc *crtc) { };
      |                    ^~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c:61:6: error: redefinition of 'rzg2l_du_vsp_disable'
   61 | void rzg2l_du_vsp_disable(struct rzg2l_du_crtc *crtc)
      |      ^~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.h:73:20: note: previous definition of 'rzg2l_du_vsp_disable' with type 'void(struct rzg2l_du_crtc *)'
   73 | static inline void rzg2l_du_vsp_disable(struct rzg2l_du_crtc *crtc) { };
      |                    ^~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c:66:6: error: redefinition of 'rzg2l_du_vsp_atomic_flush'
   66 | void rzg2l_du_vsp_atomic_flush(struct rzg2l_du_crtc *crtc)
      |      ^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.h:74:20: note: previous definition of 'rzg2l_du_vsp_atomic_flush' with type 'void(struct rzg2l_du_crtc *)'
   74 | static inline void rzg2l_du_vsp_atomic_flush(struct rzg2l_du_crtc *crtc) { };
      |                    ^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c:76:19: error: redefinition of 'rzg2l_du_vsp_get_drm_plane'
   76 | struct drm_plane *rzg2l_du_vsp_get_drm_plane(struct rzg2l_du_crtc *crtc,
      |                   ^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.h:75:33: note: previous definition of 'rzg2l_du_vsp_get_drm_plane' with type 'struct drm_plane *(struct rzg2l_du_crtc *, unsigned int)'
   75 | static inline struct drm_plane *rzg2l_du_vsp_get_drm_plane(struct rzg2l_du_crtc *crtc,
      |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.c:302:5: error: redefinition of 'rzg2l_du_vsp_init'
  302 | int rzg2l_du_vsp_init(struct rzg2l_du_vsp *vsp, struct device_node *np,
      |     ^~~~~~~~~~~~~~~~~
drivers/gpu/drm/renesas/rz-du/rzg2l_du_vsp.h:66:19: note: previous definition of 'rzg2l_du_vsp_init' with type 'int(struct rzg2l_du_vsp *, struct device_node *, unsigned int)'
   66 | static inline int rzg2l_du_vsp_init(struct rzg2l_du_vsp *vsp, struct device_node *np,
      |                   ^~~~~~~~~~~~~~~~~
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/linux-next/20240222124610.383e1ce3@canb.auug.org.au/T/#uSigned-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 768e9e61 ("drm: renesas: Add RZ/G2L DU Support")
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240222112643.110326-1-biju.das.jz@bp.renesas.com