UPSTREAM: drm/amd/display: set dcn315 lb bpp to 48

commit 6d9240c4 upstream.

[Why & How]
Fix a typo for dcn315 line buffer bpp.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Change-Id: I6f5408cd982d1ff478e6fb2982bd90c97184e692
Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 4ac57c3f)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>