staging: media: tegra-video: use BIT() macro instead of shift

Replace two instances of (1 << X) with BIT(X) in tegra20.c to follow
kernel coding style guidelines and improve clarity. The BIT() macro
also ensures proper type handling for larger shifts.

Signed-off-by: A.T. Jefferies <alextjefferies@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>