[ Upstream commit aee50bd88ea5fde1ff4cc021385598f81a65830c ]
Added checks for xoffset, yoffset settings.
Incorrect settings of these parameters can lead to errors
in sm501fb_pan_ functions.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: 5fc404e47b ("[PATCH] fb: SM501 framebuffer driver")
Signed-off-by: Danila Chernetsov <listdansp@mail.ru>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>