drm/format-helper: Add generic conversion to 32-bit formats

drm/format-helper: Add generic conversion to 32-bit formats

[ Upstream commit d55d0b066f4eedf030c9c1a67a2a0abffece3abc ]

Add drm_fb_xfrm_line_32to32() to implement conversion from 32-bit
pixels to 32-bit pixels. The pixel-conversion is specified by the
given callback parameter. Mark the helper as always_inline to avoid
overhead from function calls.

Then implement all existing line-conversion functions with the new
generic call and the respective pixel-conversion helper.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250328141709.217283-3-tzimmermann@suse.de
Stable-dep-of: 05663d88fd0b ("drm/tests: Fix drm_test_fb_xrgb8888_to_xrgb2101010() on big-endian")
Signed-off-by: Sasha Levin <sashal@kernel.org>