drm/mipi-dsi: Add a mipi_dsi_dcs_write_seq() macro

Many panel drivers define dsi_dcs_write_seq() and dsi_generic_write_seq()
macros to send DCS commands and generic write packets respectively, with
the payload specified as a list of parameters instead of using arrays.

There's already a macro for the former, introduced by commit 2a9e9daf
("drm/mipi-dsi: Introduce mipi_dsi_dcs_write_seq macro") so drivers can be
changed to use that. But there isn't one yet for the latter, let's add it.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230102202542.3494677-2-javierm@redhat.com