drm/imx/ipuv3: Fix dumb-buffer allocation for non-RGB formats

drm/imx/ipuv3: Fix dumb-buffer allocation for non-RGB formats

Align pitch to multiples of 8 pixels for bpp values that do not map
to RGB formats. The call to drm_driver_color_mode_format() fails with
DRM_INVALID_FORMAT in these cases. Fall back to manually computing
the pitch alignment from which drm_mode_size_dumb() can compute the
correct pitch.

Fixes userspace that allocates dumb buffers for YUV formats, where
bpp equals 12. A common example is the IGT kms_getfb test.

v2:
- ignore width in calculation

Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: b1d0e470f881 ("drm/imx/ipuv3: Compute dumb-buffer sizes with drm_mode_size_dumb()")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Cc: imx@lists.linux.dev
Cc: linux-arm-kernel@lists.infradead.org
Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://patch.msgid.link/20251104153832.189666-1-tzimmermann@suse.de