fbdev: hpfb: Fix an error handling path in hpfb_dio_probe()

[ Upstream commit aa578e897520f32ae12bec487f2474357d01ca9c ]

If an error occurs after request_mem_region(), a corresponding
release_mem_region() should be called, as already done in the remove
function.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>