video/fbdev/stifb: Implement the stifb_fillrect() function

stable inclusion
from stable-v5.10.154
commit f8c86d7829525e1b0ea4ee232b967661cf7de4cb
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I64YCB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f8c86d7829525e1b0ea4ee232b967661cf7de4cb



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[ Upstream commit 9c379c65 ]

The stifb driver (for Artist/HCRX graphics on PA-RISC) was missing
the fillrect function.
Tested on a 715/64 PA-RISC machine and in qemu.

Signed-off-by: Helge Deller <deller@gmx.de>
Stable-dep-of: 776d875f ("fbdev: stifb: Fall back to cfb_fillrect() on 32-bit HCRX cards")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Lipeng Sang <sanglipeng1@jd.com>