drm/radeon: make -fstrict-flex-arrays=3 happy

[ Upstream commit 0ba753b ]

The driver parses a union where the layout up through the first
array is the same, however, the array has different sizes
depending on the elements in the union.  Be explicit to
fix the UBSAN checker.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3323
Fixes: df8fc4e ("kbuild: Enable -fstrict-flex-arrays=3")
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -922,8 +922,12 @@ bool radeon_get_atom_connector_info_from_supported_devices_table(struct
 		max_device = ATOM_MAX_SUPPORTED_DEVICE_INFO;
 
 	for (i = 0; i < max_device; i++) {
-		ATOM_CONNECTOR_INFO_I2C ci =
-		    supported_devices->info.asConnInfo[i];
+		ATOM_CONNECTOR_INFO_I2C ci;
+
+		if (frev > 1)
+			ci = supported_devices->info_2d1.asConnInfo[i];
+		else
+			ci = supported_devices->info.asConnInfo[i];
 
 		bios_connectors[i].valid = false;