drm/tegra: Zero-initialize iosys_map

[ Upstream commit 3868ff00 ]

UBSAN reports an invalid load for bool, as the iosys_map is read
later without being initialized. Zero-initialize it to avoid this.

Reported-by: Ashish Mhetre <amhetre@nvidia.com>
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230901115910.701518-2-cyndis@kapsi.fi


Signed-off-by: Sasha Levin <sashal@kernel.org>