Remove invalid uses of rsvd1 from Beaver device tree. Replace by actual
function names of pinmux option 1.

Taken from https://github.com/NVIDIA/tegra-pinmux-scripts commit
b0aceda108c0 ("remove invalid uses of rsvd1 from beaver config").
Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>